The update of the share of a cfs_rq is done when its load_avg is updated
but before the group_entity's load_avg has been updated for the past time
slot. This generates wrong load_avg accounting which can be significant
when small tasks are involved in the scheduling.
Let take the example of a task a that is dequeued of its task group A:
root
(cfs_rq)
\
(se)
A
(cfs_rq)
\
(se)
a
Task "a" was the only task in task group A which becomes idle when a is
dequeued.
We have the sequence:
- dequeue_entity a->se
- update_load_avg(a->se)
- dequeue_entity_load_avg(A->cfs_rq, a->se)
- update_cfs_shares(A->cfs_rq)
A->cfs_rq->load.weight == 0
A->se->load.weight is updated with the new share (0 in this case)
- dequeue_entity A->se
- update_load_avg(A->se) but its weight is now null so the last time
slot (up to a tick) will be accounted with a weight of 0 instead of
its real weight during the time slot. The last time slot will be
accounted as an idle one whereas it was a running one.
If the running time of task a is short enough that no tick happens when it
runs, all running time of group entity A->se will be accounted as idle
time.
Instead, we should update the share of a cfs_rq (in fact the weight of its
group entity) only after having updated the load_avg of the group_entity.
update_cfs_shares() now takes the sched_entity as a parameter instead of the
cfs_rq, and the weight of the group_entity is updated only once its load_avg
has been synced with current time.
Change-Id: Id6ce3be1767b44b444ce2a77ed1ba063e57c0664
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pjt@google.com
Link: http://lkml.kernel.org/r/1482335426-7664-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 89ee048f3cc796db6f26906c6bef4edf0bee70fd)
[minor cherry pick stuff]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Commit:
fde7d22e01 ("sched/fair: Fix overly small weight for interactive group entities")
did something non-obvious but also did it buggy yet latent.
The problem was exposed for real by a later commit in the v4.7 merge window:
2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels")
... after which tg->load_avg and cfs_rq->load.weight had different
units (10 bit fixed point and 20 bit fixed point resp.).
Add a comment to explain the use of cfs_rq->load.weight over the
'natural' cfs_rq->avg.load_avg and add scale_load_down() to correct
for the difference in unit.
Since this is (now, as per a previous commit) the only user of
calc_tg_weight(), collapse it.
The effects of this bug should be randomly inconsistent SMP-balancing
of cgroups workloads.
Change-Id: If1e565662ea163485edd94a12aef644d0e0dfe7a
Reported-by: Jirka Hladky <jhladky@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels")
Fixes: fde7d22e01 ("sched/fair: Fix overly small weight for interactive group entities")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit ea1dc6fc6242f991656e35e2ed3d90ec1cd13418)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
A scheduler performance regression has been reported by Joseph Salisbury,
which he bisected back to:
3d30544f0212 ("sched/fair: Apply more PELT fixes)
The regression triggers when several levels of task groups are involved
(read: SystemD) and cpu_possible_mask != cpu_present_mask.
The root cause is that group entity's load (tg_child->se[i]->avg.load_avg)
is initialized to scale_load_down(se->load.weight). During the creation of
a child task group, its group entities on possible CPUs are attached to
parent's cfs_rq (tg_parent) and their loads are added to the parent's load
(tg_parent->load_avg) with update_tg_load_avg().
But only the load on online CPUs will then be updated to reflect real load,
whereas load on other CPUs will stay at the initial value.
The result is a tg_parent->load_avg that is higher than the real load, the
weight of group entities (tg_parent->se[i]->load.weight) on online CPUs is
smaller than it should be, and the task group gets a less running time than
what it could expect.
( This situation can be detected with /proc/sched_debug. The ".tg_load_avg"
of the task group will be much higher than sum of ".tg_load_avg_contrib"
of online cfs_rqs of the task group. )
The load of group entities don't have to be intialized to something else
than 0 because their load will increase when an entity is attached.
Change-Id: Ie55021ff98ba49016adfddb2444e9c9709939226
Reported-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@vger.kernel.org> # 4.8.x
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: joonwoop@codeaurora.org
Fixes: 3d30544f0212 ("sched/fair: Apply more PELT fixes)
Link: http://lkml.kernel.org/r/1476881123-10159-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit b5a9b340789b2b24c6896bcf7a065c31a4db671c)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Starting with the following commit:
fde7d22e01 ("sched/fair: Fix overly small weight for interactive group entities")
calc_tg_weight() doesn't compute the right value as expected by effective_load().
The difference is in the 'correction' term. In order to ensure \Sum
rw_j >= rw_i we cannot use tg->load_avg directly, since that might be
lagging a correction on the current cfs_rq->avg.load_avg value.
Therefore we use tg->load_avg - cfs_rq->tg_load_avg_contrib +
cfs_rq->avg.load_avg.
Now, per the referenced commit, calc_tg_weight() doesn't use
cfs_rq->avg.load_avg, as is later used in @w, but uses
cfs_rq->load.weight instead.
So stop using calc_tg_weight() and do it explicitly.
The effects of this bug are wake_affine() making randomly
poor choices in cgroup-intense workloads.
Change-Id: I1c0058ff674650cf295c8dc3b88a5a3de4bddab0
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # v4.3+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: fde7d22e01 ("sched/fair: Fix overly small weight for interactive group entities")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 7dd4912594daf769a46744848b05bd5bc6d62469)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
A task can be asynchronously detached from cfs_rq when migrating
between CPUs. The load of the migrated task is then removed from
source cfs_rq during its next update. We use this event to set
propagation flag.
During the load balance, we take advantage of the update of blocked
load to propagate any pending changes.
The propagation relies on patch:
"sched: Fix hierarchical order in rq->leaf_cfs_rq_list"
... which orders children and parents, to ensure that it's done in one pass.
Change-Id: I33782e35fc4711f5901e8c23d6aa7ec5f2ff7ee5
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-6-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 4e5160766fcc9f41bbd38bac11f92dce993644aa)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
When a task moves from/to a cfs_rq, we set a flag which is then used to
propagate the change at parent level (sched_entity and cfs_rq) during
next update. If the cfs_rq is throttled, the flag will stay pending until
the cfs_rq is unthrottled.
For propagating the utilization, we copy the utilization of group cfs_rq to
the sched_entity.
For propagating the load, we have to take into account the load of the
whole task group in order to evaluate the load of the sched_entity.
Similarly to what was done before the rewrite of PELT, we add a correction
factor in case the task group's load is greater than its share so it will
contribute the same load of a task of equal weight.
Change-Id: Id34a9888484716961c9027299c0b4d82881a39d1
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-5-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 09a43ace1f986b003c118fdf6ddf1fd685692d49)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Fix the insertion of cfs_rq in rq->leaf_cfs_rq_list to ensure that a
child will always be called before its parent.
The hierarchical order in shares update list has been introduced by
commit:
67e86250f8 ("sched: Introduce hierarchal order on shares update list")
With the current implementation a child can be still put after its
parent.
Lets take the example of:
root
\
b
/\
c d*
|
e*
with root -> b -> c already enqueued but not d -> e so the
leaf_cfs_rq_list looks like: head -> c -> b -> root -> tail
The branch d -> e will be added the first time that they are enqueued,
starting with e then d.
When e is added, its parents is not already on the list so e is put at
the tail : head -> c -> b -> root -> e -> tail
Then, d is added at the head because its parent is already on the
list: head -> d -> c -> b -> root -> e -> tail
e is not placed at the right position and will be called the last
whereas it should be called at the beginning.
Because it follows the bottom-up enqueue sequence, we are sure that we
will finished to add either a cfs_rq without parent or a cfs_rq with a
parent that is already on the list. We can use this event to detect
when we have finished to add a new branch. For the others, whose
parents are not already added, we have to ensure that they will be
added after their children that have just been inserted the steps
before, and after any potential parents that are already in the list.
The easiest way is to put the cfs_rq just after the last inserted one
and to keep track of it untl the branch is fully added.
Change-Id: I4fe0b8502ea628c13d14e8e5c5279bce67fb8845
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 9c2791f936ef5fd04a118b5c284f2c9a95f4a647)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Every time we modify load/utilization of sched_entity, we start to
sync it with its cfs_rq. This update is done in different ways:
- when attaching/detaching a sched_entity, we update cfs_rq and then
we sync the entity with the cfs_rq.
- when enqueueing/dequeuing the sched_entity, we update both
sched_entity and cfs_rq metrics to now.
Use update_load_avg() everytime we have to update and sync cfs_rq and
sched_entity before changing the state of a sched_enity.
Change-Id: Ibde9a7e07ac80e9d5753bb4a0c30dfb3643cc666
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[backported FROMLIST]
Signed-off-by: Andres Oportus <andresoportus@google.com>
(cherry picked from commit d31b1a66cbe0931733583ad9d9e8c6cfd710907d)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Vincent noted that the update_tg_load_avg() usage in commit:
3d30544f0212 ("sched/fair: Apply more PELT fixes")
isn't entirely sufficient. We need to call this function every time
cfs_rq->avg.load changes, this includes when update_cfs_rq_load_avg()
returns true, but {attach,detach}_entity_load_avg() themselves also
change it. This means we need to unconditionally call
update_tg_load_avg().
Also, add more comments.
Change-Id: I7e55fceb587601f73c760c8b0d47a7ef2b777b9e
Reported-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 7c3edd2c300b7ef2005a69dc727692ee07434aa5)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
One additional 'rule' for using update_cfs_rq_load_avg() is that one
should call update_tg_load_avg() if it returns true.
Add a bunch of comments to hopefully clarify some of the rules:
o You need to update cfs_rq _before_ any entity attach/detach,
this is important, because while for mathmatical consisency this
isn't strictly needed, it is required for the physical
interpretation of the model, you attach/detach _now_.
o When you modify the cfs_rq avg, you have to then call
update_tg_load_avg() in order to propagate changes upwards.
o (Fair) entities are always attached, switched_{to,from}_fair()
deal with !fair. This directly follows from the definition of the
cfs_rq averages, namely that they are a direct sum of all
(runnable or blocked) entities on that rq.
It is the second rule that this patch enforces, but it adds comments
pertaining to all of them.
Change-Id: Icdc906e98c67b84cb9582c893bc761a9886be57a
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 3d30544f02120b884bba2a9466c87dba980e3be5)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
A new task's util_avg is set to full utilization of a CPU (100% time
running). This accelerates a new task's utilization ramp-up, useful to
boost its execution in early time. However, it may result in
(insanely) high utilization for a transient time period when a flood
of tasks are spawned. Importantly, it violates the "fundamentally
bounded" CPU utilization, and its side effect is negative if we don't
take any measure to bound it.
This patch proposes an algorithm to address this issue. It has
two methods to approach a sensible initial util_avg:
(1) An expected (or average) util_avg based on its cfs_rq's util_avg:
util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight
(2) A trajectory of how successive new tasks' util develops, which
gives 1/2 of the left utilization budget to a new task such that
the additional util is noticeably large (when overall util is low) or
unnoticeably small (when overall util is high enough). In the meantime,
the aggregate utilization is well bounded:
util_avg_cap = (1024 - cfs_rq->avg.util_avg) / 2^n
where n denotes the nth task.
If util_avg is larger than util_avg_cap, then the effective util is
clamped to the util_avg_cap.
Change-Id: Idafe989b24d9e70911666f09800bf1d5a011e1f4
Reported-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: steve.muckle@linaro.org
Link: http://lkml.kernel.org/r/1459283456-21682-1-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 2b8c41daba327c633228169e8bd8ec067ab443f8)
[integrate with schedfreq - schedfreq has a tuneable for init task util
but this commit removes the use of the tuneable since we have a new
algorithm for calculating an initial utilisation. I've left the tuneable
in place, but it is no longer used even when schedfreq is the CPUFreq
governor]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Rename best_idle to best_idle_cpu so the same name is used like in
find_best_target().
Fix if (best_idle > 0) since best_idle_cpu = 0 is a valid target.
Use 'unsigned long' data type for best_idle_capacity.
Since we're looking for the shallowest best_idle_cstate initialize
best_idle_cstate = INT_MAX. For cpus which are not idle (idle_idx = -1)
the condition 'if (idle_idx < best_idle_cstate && ...)' is never
executed.
Change-Id: Ic5b63d58478696b3d1ec6253cf739a69a574cf99
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit 8bff5e9c0968108d465e1f2a4624fc5ec2f00849)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Simplify backup_capacity handling and use 'unsigned long'
data type for cpu capacity, simplify target_util handling,
simplify idle_idx handling & refactor min_util, new_util.
Also return first idle cpu for prefer_idle task immediately.
Change-Id: Ic89e140f7b369f3965703fdc8463013d16e9b94a
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
The schedtune task parameter 'boosted' is mapped into the cpu iteration
order. Currently for 'boosted' equal true the iteration starts at the
last cpu (NR_CPUS-1) whereas for 'boosted' equal false it starts at the
first cpu (0).
This only has the desired effect if the cpu topology oerdering matches
the underlying assumption. This e.g. is the case for the
Qc snapdragon 821 with its [L0 L1 b0 b1] cpu topology layout
(L=lower max freq, b=higher max freq). This results in cpus with higher
maximum capacity being given the highest logical cpu ids. However not
all big.LITTLE systems enumerate their cpus in the same way. For example,
the ARM Versatile Express Juno board has 6 cpus for which the default
configuration has topology [L0 b0 b1 L1 L2 L3].
To make this approach independent from the cpu topology layout it now
iterates over the cpus in the order of the sched_groups of the EAS
sched_domain (sd_ea). The order of cpu iteration is different for the
different cpu types in case the cpu is used to dereference sd_ea.
Considering the Qc snapdragon 821 again, for cpu L0 and L1 the order is
'b0->b1->L0->L1' whereas for b0 and b1 the order is 'b0->b1->L0->L1'.
This approach does not allow the exact same iteration order as with the
currently used flat iteration over [0 .. NR_CPUS-1] but the cpus
are ordered by the original cpu capacity.
The cpu iteration is now done in the sd_ea sched_group order required by
the 'boosted' value ['L0->L1->b0->b1'/'b0->b1->L0->L1'] rather than
forward/backward over the flat cpu space ['L0->L1->b0->b1'/
'b1->b0->L1->L0'].
Change-Id: I8fbe2073dedd2ecb1c750620c6000c11a5ff4358
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit a0c6a4272c3968c0ff50d3fed65f5865b72d777b)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
This will allow to start iterating from a cpu with max or min original
capacity in the wakeup path regardless on which cpu the scheduler is
currently running (smp_processor_id()) or the previous cpu of the task
(task_cpu(p)). This iteration has to happen on a sched_domain spanning
all cpus in the order of the sched_groups of this sched_domain seen by
the starting cpu.
In case of an SMP system the first cpu with max orig capacity and the
the one with min orig capacity is the same. This can temporally happen
on a big.LITTLE system with hotplug as well.
E.g. the different order of cpu iteration can be used to map schedtune
task parameter 'boosted' into the cpu iteration order in
find_best_target().
Use of READ_ONCE()/WRITE_ONCE() to avoid load/store tearing.
Change-Id: I812fbd9c7e5f506617e456c0eec3edcd2c016e92
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit fd6e9543c1fd8971a5e2e68e39b2f6e591d46114)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Commit fd5c98da1a42 "WIP: sched: Store system-wide maximum cpu capacity
in root domain" was repalced by commit 8148bdfff4f5 "WIP: sched: Update
max cpu capacity in case of max frequency constraints" which didn't
remove all the now unused bits.
Change-Id: I067f6366431f43337cffa7a2a8e0de32dd33d2f9
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit 6d284a607cec51bcafca313bc396bc3103b1e876)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
With the new wakeup approach this sysctl is not necessary any more.
Change-Id: I52114b3c918791f6a4f9f30f50002919ccbc1a9c
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit 885c0d503bcdf0ef4e9b46822496f16b20aa3bbd)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
This patch replaces the existing EAS upstream implementation of
select_energy_cpu_brute() with the one of find_best_target() used
in Android previously.
It also removes the cpumask 'and' from select_energy_cpu_brute,
see the existing use of 'cpu = smp_processor_id()' in
select_task_rq_fair().
Change-Id: If678c002efaa87d1ba3ec9989a4e9f8df98b83ec
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
[ added guarding for non-schedtune builds ]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
This patch re-integrates the part which was initially provided by
3b9d7554aeec ("EAS: sched/fair: tunable to honor sync wakeups") into
energy_aware_wake_cpu() into select_energy_cpu_brute().
Change-Id: I748fde3ecdeb44651179bce0a5bb8dd82d1903f6
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit b75b7286cb068d5761621ea134c23dd131db953f)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
This has to be done in the caller function of energy_diff() version of
SchedTune to avoid Null pointer dereference in energy_diff().
Change-Id: I3f0f68dbd11efb15bbb3b1832f8294419ed85241
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit 14531d4e245d063f713ee5ed835df958e6c7838f)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
When the systems is not overutilized, place waking tasks on the most
energy efficient cpu. Previous attempts reduced the search space by
matching task utilization to cpu capacity before consulting the energy
model as this is an expensive operation. The search heuristics didn't
work very well and lacking any better alternatives this patch takes the
brute-force route and tries all potential targets.
This approach doesn't scale, but it might be sufficient for many
embedded applications while work is continuing on a heuristic that can
minimize the necessary computations. The heuristic must be derrived from
the platform energy model rather than make additional assumptions, such
lower capacity implies better energy efficiency. PeterZ mentioned in the
past that we might be able to derrive some simpler deciding functions
using mathematical (modal?) analysis.
Change-Id: I772bacb4c8fd599f8006fa422f842e66377a9c6c
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
[rebase: on top of msm-google/android-msm-marlin-3.18]
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit a894422dbdb7b77ea2acfe7ff909ccb5ded23514)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
It is not worth the overhead to migrate tasks for tiny insignificant
energy savings. To prevent this, an energy margin is introduced in
energy_diff() which effectively adds a dead-zone that rounds tiny energy
differences to zero. Since no scale is enforced for energy model data
the margin can't be absolute. Instead it is defined as +/-1.56% energy
saving compared to the current total estimated energy consumption.
Change-Id: I6be069c752c701fb825430896b3b768a7ab2fee4
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
[rebase: on top of msm-google/android-msm-marlin-3.18,
massage original patch which changes code in energy_diff()
into __energy_diff() introduced by SchedTune]
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
(cherry picked from commit 780cb5a5fa47adf13d4fc2b77e8e94448cd56098)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
The EAS functionality in the wakeup path will be brought back by the
following patch ("sched/fair: Energy-aware wake-up task placement")
providing the function select_energy_cpu_brute().
Change-Id: I927fb9e8261cfacfe404695f853941c7959aa146
[ Trivial merge conflicts resolved. ]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit 80aee424fb7765a777267e144037642625a71304)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
This lets us use Capacity-Aware Scheduling (CAS) if EAS is enabled.
Change-Id: I2e647a201ea0b733d1487c3e153047a49fb22847
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit 00b7da2ae58bf568529e67614980f77e275b8d29)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
For asymmetric CPU capacity systems it is counter-productive for
throughput if low capacity CPUs are pulling tasks from non-overloaded
CPUs with higher capacity. The assumption is that higher CPU capacity is
preferred over running alone in a group with lower CPU capacity.
This patch rejects higher CPU capacity groups with one or less task per
CPU as potential busiest group which could otherwise lead to a series of
failing load-balancing attempts leading to a force-migration.
Change-Id: I428875bb6267c780026ef75e2882300738d016e7
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-5-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 9e0994c0a1c1f82c705f1f66388e1bcffcee8bb9)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
struct sched_group_capacity currently represents the compute capacity
sum of all CPUs in the sched_group.
Unless it is divided by the group_weight to get the average capacity
per CPU, it hides differences in CPU capacity for mixed capacity systems
(e.g. high RT/IRQ utilization or ARM big.LITTLE).
But even the average may not be sufficient if the group covers CPUs of
different capacities.
Instead, by extending struct sched_group_capacity to indicate min per-CPU
capacity in the group a suitable group for a given task utilization can
more easily be found such that CPUs with reduced capacity can be avoided
for tasks with high utilization (not implemented by this patch).
Change-Id: If3cae1be62d01a199e752bca5abb45357d5d0fbd
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-4-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit bf475ce0a3dd75b5d1df6c6c14ae25168caa15ac)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
In low-utilization scenarios comparing relative loads in
find_idlest_group() doesn't always lead to the most optimum choice.
Systems with groups containing different numbers of cpus and/or cpus of
different compute capacity are significantly better off when considering
spare capacity rather than relative load in those scenarios.
In addition to existing load based search an alternative spare capacity
based candidate sched_group is found and selected instead if sufficient
spare capacity exists. If not, existing behaviour is preserved.
Change-Id: I6097af76c302a5a12e240ca24c70f707ad118242
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-3-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 6a0b19c0f39a7a7b7fb77d3867a733136ff059a3)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
At task wake-up load-tracking isn't updated until the task is enqueued.
The task's own view of its utilization contribution may therefore not be
aligned with its contribution to the cfs_rq load-tracking which may have
been updated in the meantime. Basically, the task's own utilization
hasn't yet accounted for the sleep decay, while the cfs_rq may have
(partially). Estimating the cfs_rq utilization in case the task is
migrated at wake-up as task_rq(p)->cfs.avg.util_avg - p->se.avg.util_avg
is therefore incorrect as the two load-tracking signals aren't time
synchronized (different last update).
To solve this problem, this patch synchronizes the task utilization with
its previous rq before the task utilization is used in the wake-up path.
Currently the update/synchronization is done _after_ the task has been
placed by select_task_rq_fair(). The synchronization is done without
having to take the rq lock using the existing mechanism used in
remove_entity_load_avg().
Change-Id: I5605cca0c94c6ba43d9ce11554765a2456cf85bc
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-2-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 104cb16d9eb684f071d5bf3aa87c0d01af259b7c)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Currently, SD_WAKE_AFFINE always takes priority over wakeup balancing if
SD_BALANCE_WAKE is set on the sched_domains. For asymmetric
configurations SD_WAKE_AFFINE is only desirable if the waking task's
compute demand (utilization) is suitable for the waking CPU and the
previous CPU, and all CPUs within their respective
SD_SHARE_PKG_RESOURCES domains (sd_llc). If not, let wakeup balancing
take over (find_idlest_{group, cpu}()).
This patch makes affine wake-ups conditional on whether both the waker
CPU and the previous CPU has sufficient capacity for the waking task,
or not, assuming that the CPU capacities within an SD_SHARE_PKG_RESOURCES
domain (sd_llc) are homogeneous.
Change-Id: I6d5d0426713da9ef6198f574ad9afbe58dacc1f0
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1469453670-2660-10-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 3273163c6775c4c21823985304c2364b08ca6ea2)
[removed existing definition of capacity_margin]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
A domain with the SD_ASYM_CPUCAPACITY flag set indicate that
sched_groups at this level and below do not include CPUs of all
capacities available (e.g. group containing little-only or big-only CPUs
in big.LITTLE systems). It is therefore necessary to put in more effort
in finding an appropriate CPU at task wake-up by enabling balancing at
wake-up (SD_BALANCE_WAKE) on all lower (child) levels.
Change-Id: I4615917f540d03d7e7ef7de8f0da33b1ad97387c
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1469453670-2660-8-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 9ee1cda5ee25c7dd82acf25892e0d229e818f8c7)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
If behavioural sched_domain flags depend on topology flags set at higher
domain levels we need a way to update the child domain flags. Moving the
child pointer assignment inside sd_init() should make that possible.
Change-Id: If043921fdf102c310adcc9e0280afa33c48c4783
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1469453670-2660-7-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 3676b13e8524c576825fe1e731e347dba0083888)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Add a topology flag to the sched_domain hierarchy indicating the lowest
domain level where the full range of CPU capacities is represented by
the domain members for asymmetric capacity topologies (e.g. ARM
big.LITTLE).
The flag is intended to indicate that extra care should be taken when
placing tasks on CPUs and this level spans all the different types of
CPUs found in the system (no need to look further up the domain
hierarchy). This information is currently only available through
iterating through the capacities of all the CPUs at parent levels in the
sched_domain hierarchy.
SD 2 [ 0 1 2 3] SD_ASYM_CPUCAPACITY
SD 1 [ 0 1] [ 2 3] !SD_ASYM_CPUCAPACITY
CPU: 0 1 2 3
capacity: 756 756 1024 1024
If the topology in the example above is duplicated to create an eight
CPU example with third sched_domain level on top (SD 3), this level
should not have the flag set (!SD_ASYM_CPUCAPACITY) as its two group
would both have all CPU capacities represented within them.
Change-Id: I1526407b90567cac387419719b7d7fdc8b259a85
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1469453670-2660-6-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 1f6e6c7cb9bcd58abb5ee11243e0eefe6b36fc8e)
[trivial merge conflict]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
In the current find_idlest_group()/find_idlest_cpu() search we end up
calling find_idlest_cpu() in a sched_group containing only one CPU in
the end. Checking idle-states becomes pointless when there is no
alternative, so bail out instead.
Change-Id: Ic62bf09b53a7984143ac2431aaa69c69b204cd56
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: linux-kernel@vger.kernel.org
Cc: mgalbraith@suse.de
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1466615004-3503-4-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit eaecf41f5abf80b63c8e025fcb9ee4aa203c3038)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
In commit:
ac66f54772 ("sched/numa: Introduce migrate_swap()")
select_task_rq() got a 'cpu' argument to enable overriding of prev_cpu
in special cases (NUMA task swapping).
However, the select_task_rq_fair() helper functions: wake_affine() and
select_idle_sibling(), still use task_cpu(p) directly to work out
prev_cpu, which leads to inconsistencies.
This patch passes prev_cpu (potentially overridden by NUMA code) into
the helper functions to ensure prev_cpu is indeed the same CPU
everywhere in the wakeup path.
Change-Id: I4951c4eead2e6045e4fb34e89f6cda17d881d4d7
cc: Ingo Molnar <mingo@redhat.com>
cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: linux-kernel@vger.kernel.org
Cc: mgalbraith@suse.de
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1466615004-3503-3-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 772bd008cd9a1d4e8ce566f2edcc61d1c28fcbe5)
[merged with Android/EAS wakeup path]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Revert the changes in find_idlest_cpu() and find_idlest_group().
Keep the infrastructure bits which are used in following EAS patches.
Change-Id: Id516ca5f3e51b9a13db1ebb8de2df3aa25f9679b
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
The rate_limit_us tunable is intended to reduce the possible overhead
from running the schedutil governor. However, that overhead can be
divided into two separate parts: the governor computations and the
invocation of the scaling driver to set the CPU frequency. The latter
is where the real overhead comes from. The former is much less
expensive in terms of execution time and running it every time the
governor callback is invoked by the scheduler, after rate_limit_us
interval has passed since the last frequency update, would not be a
problem.
For this reason, redefine the rate_limit_us tunable so that it means the
minimum time that has to pass between two consecutive invocations of the
scaling driver by the schedutil governor (to set the CPU frequency).
Change-Id: Iced64116b826c25441ef537c27a3dabfcf81919e
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[pulled from linux-pm linux-next https://patchwork.kernel.org/patch/9583949/ ]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
The rate-limit tunable in the schedutil governor applies to transitions
to both lower and higher frequencies. On several platforms it is not the
ideal tunable though, as it is difficult to get best power/performance
figures using the same limit in both directions.
It is common on mobile platforms with demanding user interfaces to want
to increase frequency rapidly for example but decrease slowly.
One of the example can be a case where we have short busy periods
followed by similar or longer idle periods. If we keep the rate-limit
high enough, we will not go to higher frequencies soon enough. On the
other hand, if we keep it too low, we will have too many frequency
transitions, as we will always reduce the frequency after the busy
period.
It would be very useful if we can set low rate-limit while increasing
the frequency (so that we can respond to the short busy periods quickly)
and high rate-limit while decreasing frequency (so that we don't reduce
the frequency immediately after the short busy period and that may avoid
frequency transitions before the next busy period).
Implement separate up/down transition rate limits. Note that the
governor avoids frequency recalculations for a period equal to minimum
of up and down rate-limit. A global mutex is also defined to protect
updates to min_rate_limit_us via two separate sysfs files.
Note that this wouldn't change behavior of the schedutil governor for
the platforms which wish to keep same values for both up and down rate
limits.
This is tested with the rt-app [1] on ARM Exynos, dual A15 processor
platform.
Testcase: Run a SCHED_OTHER thread on CPU0 which will emulate work-load
for X ms of busy period out of the total period of Y ms, i.e. Y - X ms
of idle period. The values of X/Y taken were: 20/40, 20/50, 20/70, i.e
idle periods of 20, 30 and 50 ms respectively. These were tested against
values of up/down rate limits as: 10/10 ms and 10/40 ms.
For every test we noticed a performance increase of 5-10% with the
schedutil governor, which was very much expected.
[Viresh]: Simplified user interface and introduced min_rate_limit_us +
mutex, rewrote commit log and included test results.
[1] https://github.com/scheduler-tools/rt-app/
Change-Id: I18720a83855b196b8e21dcdc8deae79131635b84
Signed-off-by: Steve Muckle <smuckle.linux@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
(applied from https://marc.info/?l=linux-kernel&m=147936011103832&w=2)
[trivial adaptations]
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
If WALT is available and enabled, make schedutil governor use its
utilization signal.
Change-Id: I92bc37989447a76616e9bcc4e9e8616774fb9925
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
[we need to use boosted_cpu_util for schedutil, so make it
not static]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
A policy of going to fmax on any RT activity will be detrimental
for power on many platforms. Often RT accounts for only a small amount
of CPU activity so sending the CPU frequency to fmax is overkill. Worse
still, some platforms may not be able to even complete the CPU frequency
change before the RT activity has already completed.
Cpufreq governors have not treated RT activity this way in the past so
it is not part of the expected semantics of the RT scheduling class. The
DL class offers guarantees about task completion and could be used for
this purpose.
Modify the schedutil algorithm to instead use rt_avg as an estimate of
RT utilization of the CPU.
Based on previous work by Vincent Guittot <vincent.guittot@linaro.org>.
Change-Id: I1ed605a3e2512a94d34217a8e57c3fd97cca60be
Signed-off-by: Steve Muckle <smuckle@linaro.org>
If slow path frequency changes are conducted in a SCHED_OTHER context
then they may be delayed for some amount of time, including
indefinitely, when real time or deadline activity is taking place.
Move the slow path to a real time kernel thread. In the future the
thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set
to 50 for now.
Hackbench results on ARM Exynos, dual core A15 platform for 10
iterations:
$ hackbench -s 100 -l 100 -g 10 -f 20
Before After
---------------------------------
1.808 1.603
1.847 1.251
2.229 1.590
1.952 1.600
1.947 1.257
1.925 1.627
2.694 1.620
1.258 1.621
1.919 1.632
1.250 1.240
Average:
1.8829 1.5041
Based on initial work by Steve Muckle.
Change-Id: I8f53037e94f353960c6d10abf07822d671631ef7
Signed-off-by: Steve Muckle <smuckle.linux@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from 02a7b1ee3baa)
[adapt to the 3.18 kthread interface]
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
The schedfreq governor does not currently handle cpufreq drivers which
use a global set of tunables (!have_governor_per_policy).
For example on x86 and using the acpi cpufreq driver, doing this
cat /sys/devices/system/cpu/cpufreq/sched/up_throttle_nsec
will result in a bad pointer access.
Update the tunable code using the upstream schedutil tunable code by
Rafael Wysocki as a guide.
Includes a partial backport of the reorganized cpufreq tunable
infrastructure.
Change-Id: I7e6f8de1dac297077ad43f37dd2f6ddbfe921c98
Signed-off-by: Steve Muckle <smuckle@linaro.org>
[fixed cherry-pick issue]
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
[fixed cherry-pick issue]
Signed-off-by: Thierry Strudel <tstrudel@google.com>
Add a new cpufreq scaling governor, called "schedutil", that uses
scheduler-provided CPU utilization information as input for making
its decisions.
Doing that is possible after commit 34e2c55 (cpufreq: Add
mechanism for registering utilization update callbacks) that
introduced cpufreq_update_util() called by the scheduler on
utilization changes (from CFS) and RT/DL task status updates.
In particular, CPU frequency scaling decisions may be based on
the the utilization data passed to cpufreq_update_util() by CFS.
The new governor is relatively simple.
The frequency selection formula used by it depends on whether or not
the utilization is frequency-invariant. In the frequency-invariant
case the new CPU frequency is given by
next_freq = 1.25 * max_freq * util / max
where util and max are the last two arguments of cpufreq_update_util().
In turn, if util is not frequency-invariant, the maximum frequency in
the above formula is replaced with the current frequency of the CPU:
next_freq = 1.25 * curr_freq * util / max
The coefficient 1.25 corresponds to the frequency tipping point at
(util / max) = 0.8.
All of the computations are carried out in the utilization update
handlers provided by the new governor. One of those handlers is
used for cpufreq policies shared between multiple CPUs and the other
one is for policies with one CPU only (and therefore it doesn't need
to use any extra synchronization means).
The governor supports fast frequency switching if that is supported
by the cpufreq driver in use and possible for the given policy.
In the fast switching case, all operations of the governor take
place in its utilization update handlers. If fast switching cannot
be used, the frequency switch operations are carried out with the
help of a work item which only calls __cpufreq_driver_target()
(under a mutex) to trigger a frequency update (to a value already
computed beforehand in one of the utilization update handlers).
Currently, the governor treats all of the RT and DL tasks as
"unknown utilization" and sets the frequency to the allowed
maximum when updated from the RT or DL sched classes. That
heavy-handed approach should be replaced with something more
subtle and specifically targeted at RT and DL tasks.
The governor shares some tunables management code with the
"ondemand" and "conservative" governors and uses some common
definitions from cpufreq_governor.h, but apart from that it
is stand-alone.
Change-Id: I03876e622768e4b3ee4dc28682af7cce771f2f4c
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
(cherry-picked from 9bdcb44e391da5c41b98573bf0305a0e0b1c9569)
[ Backport the schedutil cpufreq governor from 4.9. Some cpufreq
tunable infrastructure as well as the resolve_freq API is also
backported as those are dependencies]
Signed-off-by: Steve Muckle <smuckle@linaro.org>
[trivial cherry-picking fixes]
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
[fixed default governor machinery]
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
The scheduler cpufreq hooks are required by the schedutil cpufreq
governor.
Change-Id: Ied6c46262bb33b7e81bbb3d3d2761124e0c676b7
Signed-off-by: Steve Muckle <smuckle@linaro.org>
[trivial cherry-picking fixes]
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
-----BEGIN PGP SIGNATURE-----
iQIzBAABCAAdFiEEZH8oZUiU471FcZm+ONu9yGCSaT4FAlkm0zAACgkQONu9yGCS
aT5QnxAAh9uZYFJtQ7wYngD7cQcDH1KVztqEYxCP5OtxzAZBrSNBufLdhKBbc1ZP
C04Mo+FzzNiJtBwkmlOqYaEPYUSx/uwCEk9mNX85VtchIhKBrwWF7GxkeXCPs6e5
yP5TUXmxbbSp3qM4q2Z4XSW8eEPZ2l3zoy0fkjz2kS02e4RW0yQ34dvzw0BG2urr
+9ocyVjDBoU3QNKyVw3fd1AltKesSZK0fa2vEO+TOTW6Bm3xD4egCJdOzu9saUwK
hfSKXsJ0/pf1r1iyfz2foR/Hi3i4j6vRqnneyqozT7nxEJEuBQ3B5WhnsbDfzrXu
+CY23KBkDkQ1RBngmtTQd3ABHEN1E2StpBImG5RUr+5giV6/e4rdz0/HWGMvCvAz
iWqXdgZNdCnc96HPEWaDGUKxndCxsiaJOhgZwW2zm/0drVWRE+vjsOmFLyUp2Ky1
1vnKfwlvTFU4xjQ5H44AuuSHQsv+GNEtPPIHrbBv/wg90/2VuF0aYuNYjHSsc4Ca
3YM53S6/sjQqmsKixWboax8Kh2wRrEuFbqSFQV64JjFpGau61JQFMtRNl4+FFXzm
Cm+26Fan4Wtyo5zB9xnBZbDwCOXqwTXQYUP2SejtObq+Uk2tXxF05emeta9pURF3
vdgv6N0cTPm4K3VZyBZvj8JitEr2OEaIxoUqE2BXkA1MPmbqOoI=
=Z1no
-----END PGP SIGNATURE-----
Merge 4.4.70 into android-4.4
Changes in 4.4.70
usb: misc: legousbtower: Fix buffers on stack
usb: misc: legousbtower: Fix memory leak
USB: ene_usb6250: fix DMA to the stack
watchdog: pcwd_usb: fix NULL-deref at probe
char: lp: fix possible integer overflow in lp_setup()
USB: core: replace %p with %pK
ARM: tegra: paz00: Mark panel regulator as enabled on boot
tpm_crb: check for bad response size
infiniband: call ipv6 route lookup via the stub interface
dm btree: fix for dm_btree_find_lowest_key()
dm raid: select the Kconfig option CONFIG_MD_RAID0
dm bufio: avoid a possible ABBA deadlock
dm bufio: check new buffer allocation watermark every 30 seconds
dm cache metadata: fail operations if fail_io mode has been established
dm bufio: make the parameter "retain_bytes" unsigned long
dm thin metadata: call precommit before saving the roots
dm space map disk: fix some book keeping in the disk space map
md: update slab_cache before releasing new stripes when stripes resizing
rtlwifi: rtl8821ae: setup 8812ae RFE according to device type
mwifiex: pcie: fix cmd_buf use-after-free in remove/reset
ima: accept previously set IMA_NEW_FILE
KVM: x86: Fix load damaged SSEx MXCSR register
KVM: X86: Fix read out-of-bounds vulnerability in kvm pio emulation
regulator: tps65023: Fix inverted core enable logic.
s390/kdump: Add final note
s390/cputime: fix incorrect system time
ath9k_htc: Add support of AirTies 1eda:2315 AR9271 device
ath9k_htc: fix NULL-deref at probe
drm/amdgpu: Avoid overflows/divide-by-zero in latency_watermark calculations.
drm/amdgpu: Make display watermark calculations more accurate
drm/nouveau/therm: remove ineffective workarounds for alarm bugs
drm/nouveau/tmr: ack interrupt before processing alarms
drm/nouveau/tmr: fix corruption of the pending list when rescheduling an alarm
drm/nouveau/tmr: avoid processing completed alarms when adding a new one
drm/nouveau/tmr: handle races with hw when updating the next alarm time
cdc-acm: fix possible invalid access when processing notification
proc: Fix unbalanced hard link numbers
of: fix sparse warning in of_pci_range_parser_one
iio: dac: ad7303: fix channel description
pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes
pid_ns: Fix race between setns'ed fork() and zap_pid_ns_processes()
USB: serial: ftdi_sio: fix setting latency for unprivileged users
USB: serial: ftdi_sio: add Olimex ARM-USB-TINY(H) PIDs
ext4 crypto: don't let data integrity writebacks fail with ENOMEM
ext4 crypto: fix some error handling
net: qmi_wwan: Add SIMCom 7230E
fscrypt: fix context consistency check when key(s) unavailable
f2fs: check entire encrypted bigname when finding a dentry
fscrypt: avoid collisions when presenting long encrypted filenames
sched/fair: Do not announce throttled next buddy in dequeue_task_fair()
sched/fair: Initialize throttle_count for new task-groups lazily
usb: host: xhci-plat: propagate return value of platform_get_irq()
xhci: apply PME_STUCK_QUIRK and MISSING_CAS quirk for Denverton
usb: host: xhci-mem: allocate zeroed Scratchpad Buffer
net: irda: irda-usb: fix firmware name on big-endian hosts
usbvision: fix NULL-deref at probe
mceusb: fix NULL-deref at probe
ttusb2: limit messages to buffer size
usb: musb: tusb6010_omap: Do not reset the other direction's packet size
USB: iowarrior: fix info ioctl on big-endian hosts
usb: serial: option: add Telit ME910 support
USB: serial: qcserial: add more Lenovo EM74xx device IDs
USB: serial: mct_u232: fix big-endian baud-rate handling
USB: serial: io_ti: fix div-by-zero in set_termios
USB: hub: fix SS hub-descriptor handling
USB: hub: fix non-SS hub-descriptor handling
ipx: call ipxitf_put() in ioctl error path
iio: proximity: as3935: fix as3935_write
ceph: fix recursion between ceph_set_acl() and __ceph_setattr()
gspca: konica: add missing endpoint sanity check
s5p-mfc: Fix unbalanced call to clock management
dib0700: fix NULL-deref at probe
zr364xx: enforce minimum size when reading header
dvb-frontends/cxd2841er: define symbol_rate_min/max in T/C fe-ops
cx231xx-audio: fix init error path
cx231xx-audio: fix NULL-deref at probe
cx231xx-cards: fix NULL-deref at probe
powerpc/book3s/mce: Move add_taint() later in virtual mode
powerpc/pseries: Fix of_node_put() underflow during DLPAR remove
powerpc/64e: Fix hang when debugging programs with relocated kernel
ARM: dts: at91: sama5d3_xplained: fix ADC vref
ARM: dts: at91: sama5d3_xplained: not all ADC channels are available
arm64: xchg: hazard against entire exchange variable
arm64: uaccess: ensure extension of access_ok() addr
arm64: documentation: document tagged pointer stack constraints
xc2028: Fix use-after-free bug properly
mm/huge_memory.c: respect FOLL_FORCE/FOLL_COW for thp
staging: rtl8192e: fix 2 byte alignment of register BSSIDR.
staging: rtl8192e: rtl92e_get_eeprom_size Fix read size of EPROM_CMD.
iommu/vt-d: Flush the IOTLB to get rid of the initial kdump mappings
metag/uaccess: Fix access_ok()
metag/uaccess: Check access_ok in strncpy_from_user
uwb: fix device quirk on big-endian hosts
genirq: Fix chained interrupt data ordering
osf_wait4(): fix infoleak
tracing/kprobes: Enforce kprobes teardown after testing
PCI: Fix pci_mmap_fits() for HAVE_PCI_RESOURCE_TO_USER platforms
PCI: Freeze PME scan before suspending devices
drm/edid: Add 10 bpc quirk for LGD 764 panel in HP zBook 17 G2
nfsd: encoders mustn't use unitialized values in error cases
drivers: char: mem: Check for address space wraparound with mmap()
Linux 4.4.70
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
commit 094f469172e00d6ab0a3130b0e01c83b3cf3a98d upstream.
Cgroup created inside throttled group must inherit current throttle_count.
Broken throttle_count allows to nominate throttled entries as a next buddy,
later this leads to null pointer dereference in pick_next_task_fair().
This patch initialize cfs_rq->throttle_count at first enqueue: laziness
allows to skip locking all rq at group creation. Lazy approach also allows
to skip full sub-tree scan at throttling hierarchy (not in this patch).
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Link: http://lkml.kernel.org/r/146608182119.21870.8439834428248129633.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Ben Pineau <benjamin.pineau@mirakl.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
