Commit graph

1208 commits

Author SHA1 Message Date
Hidetoshi Seto
514ec49a5f x86, mce: remove incorrect __cpuinit for intel_init_cmci()
Impact: Bug fix on UP

Referring commit cc3ca22063,
Peter removed __cpuinit annotations for mce_cpu_features()
and its successor functions, which caused troubles on UP
configurations.

However the intel_init_cmci() was introduced after that and
it also has __cpuinit annotation even though it is called from
mce_cpu_features(). Remove the annotation from that function
too.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 09:15:32 +01:00
Jaswinder Singh Rajput
f4c3c4cdb1 x86: cpu_debug add support for various AMD CPUs
Impact: Added AMD CPUs support

Added flags for various AMD CPUs.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-14 18:07:58 +01:00
Sebastian Andrzej Siewior
48f4c485c2 x86/centaur: merge 32 & 64 bit version
there should be no difference, except:

 * the 64bit variant now also initializes the padlock unit.
 * ->c_early_init() is executed again from ->c_init()
 * the 64bit fixups made into 32bit path.

Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: herbert@gondor.apana.org.au
LKML-Reference: <1237029843-28076-2-git-send-email-sebastian@breakpoint.cc>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-14 16:27:29 +01:00
Ingo Molnar
0ca0f16fd1 Merge branches 'x86/apic', 'x86/asm', 'x86/cleanups', 'x86/debug', 'x86/kconfig', 'x86/mm', 'x86/ptrace', 'x86/setup' and 'x86/urgent'; commit 'v2.6.29-rc8' into x86/core 2009-03-14 16:25:40 +01:00
Yinghai Lu
d4c90e37a2 x86: print the continous part of fixed mtrrs together
Impact: print out fewer lines

 1. print continuous range with same type together
 2. change _INFO to _DEBUG

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49BACB61.8000302@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-14 12:27:06 +01:00
Yinghai Lu
63516ef6d6 x86: fix get_mtrr() warning about smp_processor_id() with CONFIG_PREEMPT=y
Impact: fix debug warning

Jaswinder noticed that there is a warning about smp_processor_id()
in get_mtrr().

Fix it by wrapping the printout into a get/put_cpu() pair.

Reported-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <49BAB7FF.4030107@kernel.org>
[ changed to get/put_cpu(), cleaned up surrounding code a it. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-14 12:27:06 +01:00
Ingo Molnar
0f3fa48a7e x86: cpu/common.c more cleanups
Complete/fix the cleanups of cpu/common.c:

 - fix ugly warning due to asm/topology.h -> linux/topology.h change
 - standardize the style across the file
 - simplify/refactor the code flow where possible

Cc: Jaswinder Singh Rajput <jaswinder@kernel.org>
LKML-Reference: <1237009789.4387.2.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-14 10:37:34 +01:00
Ingo Molnar
62395efdb0 Merge branch 'x86/asm' into tracing/syscalls
We need the wider TIF work-mask checks in entry_32.S.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-14 09:44:08 +01:00
Jaswinder Singh Rajput
9766cdbcb2 x86: cpu/common.c cleanups
- fix various style problems
 - declare varibles before they get used
 - introduced clear_all_debug_regs
 - fix header files issues

LKML-Reference: <1237009789.4387.2.camel@localhost.localdomain>
Signed-off-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-14 08:59:50 +01:00
Andreas Herrmann
3ff42da504 x86: mtrr: don't modify RdDram/WrDram bits of fixed MTRRs
Impact: bug fix + BIOS workaround

BIOS is expected to clear the SYSCFG[MtrrFixDramModEn] on AMD CPUs
after fixed MTRRs are configured.

Some BIOSes do not clear SYSCFG[MtrrFixDramModEn] on BP (and on APs).

This can lead to obfuscation in Linux when this bit is not cleared on
BP but cleared on APs. A consequence of this is that the saved
fixed-MTRR state (from BP) differs from the fixed-MTRRs of APs --
because RdDram/WrDram bits are read as zero when
SYSCFG[MtrrFixDramModEn] is cleared -- and Linux tries to sync
fixed-MTRR state from BP to AP. This implies that Linux sets
SYSCFG[MtrrFixDramEn] and activates those bits.

More important is that (some) systems change these bits in SMM when
ACPI is enabled. Hence it is racy if Linux modifies RdMem/WrMem bits,
too.

(1) The patch modifies an old fix from Bernhard Kaindl to get
    suspend/resume working on some Acer Laptops. Bernhard's patch
    tried to sync RdMem/WrMem bits of fixed MTRR registers and that
    helped on those old Laptops. (Don't ask me why -- can't test it
    myself). But this old problem was not the motivation for the
    patch. (See http://lkml.org/lkml/2007/4/3/110)

(2) The more important effect is to fix issues on some more current systems.

    On those systems Linux panics or just freezes, see

    http://bugzilla.kernel.org/show_bug.cgi?id=11541
    (and also duplicates of this bug:
    http://bugzilla.kernel.org/show_bug.cgi?id=11737
    http://bugzilla.kernel.org/show_bug.cgi?id=11714)

    The affected systems boot only using acpi=ht, acpi=off or
    when the kernel is built with CONFIG_MTRR=n.

    The acpi options prevent full enablement of ACPI.  Obviously when
    ACPI is enabled the BIOS/SMM modfies RdMem/WrMem bits.  When
    CONFIG_MTRR=y Linux also accesses and modifies those bits when it
    needs to sync fixed-MTRRs across cores (Bernhard's fix, see (1)).
    How do you synchronize that? You can't. As a consequence Linux
    shouldn't touch those bits at all (Rationale are AMD's BKDGs which
    recommend to clear the bit that makes RdMem/WrMem accessible).
    This is the purpose of this patch. And (so far) this suffices to
    fix (1) and (2).

I suggest not to touch RdDram/WrDram bits of fixed-MTRRs and
SYSCFG[MtrrFixDramEn] and to clear SYSCFG[MtrrFixDramModEn] as
suggested by AMD K8, and AMD family 10h/11h BKDGs.
BIOS is expected to do this anyway. This should avoid that
Linux and SMM tread on each other's toes ...

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: trenn@suse.de
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090312163937.GH20716@alberich.amd.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 10:19:27 +01:00
Rusty Russell
4f0628963c cpumask: use new cpumask functions throughout x86
Impact: cleanup

1) &cpu_online_map -> cpu_online_mask
2) first_cpu/next_cpu_nr -> cpumask_first/cpumask_next
3) cpu_*_map manipulation -> init_cpu_* / set_cpu_*

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-03-13 14:49:54 +10:30
Rusty Russell
3f76a183de x86: unify cpu_callin_mask/cpu_callout_mask/cpu_initialized_mask/cpu_sibling_setup_mask
Impact: cleanup

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-03-13 14:49:54 +10:30
Rusty Russell
996867d096 cpumask: convert arch/x86/kernel/cpu/mcheck/mce_64.c
Impact: reduce kernel memory usage when CONFIG_CPUMASK_OFFSTACK=y

Simple conversion of mce_device_initialized to cpumask_var_t.  We don't
check the alloc_cpumask_var() return since it's boot-time only, and
the misc_register() in that same function isn't checked.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-03-13 14:49:51 +10:30
Rusty Russell
7ad728f981 cpumask: x86: convert cpu_sibling_map/cpu_core_map to cpumask_var_t
Impact: reduce per-cpu size for CONFIG_CPUMASK_OFFSTACK=y

In most places it's cleaner to use the accessors cpu_sibling_mask()
and cpu_core_mask() wrappers which already exist.

I couldn't avoid cleaning up the access in oprofile, either.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-03-13 14:49:50 +10:30
Ingo Molnar
f6411fe7e0 Merge branches 'sched/clock', 'sched/urgent' and 'linus' into sched/core 2009-03-13 04:50:44 +01:00
Jaswinder Singh Rajput
91219bcbdc x86: cpu_debug add write support for MSRs
Supported write flag for registers.
currently write is enabled only for PMC MSR.

[root@ht]# cat /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
0x0

[root@ht]# echo 1234 > /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
[root@ht]# cat /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
0x4d2

[root@ht]# echo 0x1234 > /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
[root@ht]# cat /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
0x1234

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 03:02:45 +01:00
Yinghai Lu
0d890355bf x86: separate mtrr cleanup/mtrr_e820 trim to separate file
Impact: cleanup

mtrr main.c is too big, seperate mtrr cleanup and mtrr e820 trim
code to another file.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49B87C7B.80809@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 02:52:19 +01:00
Yinghai Lu
c1ab7e93c6 x86: print out mtrr_range_state when user specify size
Impact: print more debug info

Keep it consistent with autodetect version.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49B87C0A.4010105@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 02:52:18 +01:00
Yinghai Lu
8ad9790588 x86: more MTRR debug printouts
Impact: improve MTRR debugging messages

There's still inefficiencies suspected with the MTRR sanitizing
code, so make sure we get all the info we need from a dmesg.

- Remove unneeded mtrr_show

 (It will only printout one time by first cpu, so it is no big deal.)

- Also print out directly from get_mtrr, because it doesn't update mtrr_state.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49B9BA5A.40108@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 02:52:18 +01:00
Jan Beulich
13c6c53282 x86, 32-bit: also use cpuinfo_x86's x86_{phys,virt}_bits members
Impact: 32/64-bit consolidation

In a first step, this allows fixing phys_addr_valid() for PAE (which
until now reported all addresses to be valid). Subsequently, this will
also allow simplifying some MTRR handling code.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <49B9101E.76E4.0078.0@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 02:37:17 +01:00
Jan Beulich
02dde8b45c x86: move various CPU initialization objects into .cpuinit.rodata
Impact: debuggability and micro-optimization

Putting whatever is possible into the (final) .rodata section increases
the likelihood of catching memory corruption bugs early, and reduces
false cache line sharing.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <49B90961.76E4.0078.0@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-12 13:13:07 +01:00
Ingo Molnar
a98fe7f342 Merge branches 'x86/asm', 'x86/debug', 'x86/mm', 'x86/setup', 'x86/urgent' and 'linus' into x86/core 2009-03-12 11:50:15 +01:00
Jaswinder Singh Rajput
8229d75438 x86: cpu architecture debug code, build fix, cleanup
move store_ldt outside the CONFIG_PARAVIRT section and
also clean up the code a bit.

Signed-off-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-11 14:52:03 +01:00
Ingo Molnar
d95c357812 Merge branch 'x86/core' into cpus4096 2009-03-11 10:49:34 +01:00
Ingo Molnar
78b020d035 Merge branches 'x86/cleanups', 'x86/kexec', 'x86/mce2' and 'linus' into x86/core 2009-03-11 10:49:15 +01:00
KOSAKI Motohiro
5490fa9673 x86, mce: use round_jiffies() instead round_jiffies_relative()
Impact: saving power _very_ little

round_jiffies() round up absolute jiffies to full second.
round_jiffies_relative() round up relative jiffies to full second.

The "t->expires" is absolute jiffies. Then, round_jiffies() should be
used instead round_jiffies_relative().

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-03-10 22:33:06 -07:00
Ingo Molnar
4dd163a051 Merge branches 'tracing/ftrace', 'tracing/textedit' and 'linus' into tracing/core 2009-03-10 22:54:23 +01:00
Jaswinder Singh Rajput
9b779edf4b x86: cpu architecture debug code
Introduce:

 cat /sys/kernel/debug/x86/cpu/*

for Intel and AMD processors to view / debug the state of each CPU.

By using this we can debug whole range of registers and other
cpu information for debugging purpose and monitor how things
are changing.

This can be useful for developers as well as for users.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
LKML-Reference: <1236701373.3387.4.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-10 18:39:45 +01:00
Ingo Molnar
8293dd6f86 Merge branch 'x86/core' into tracing/ftrace
Semantic merge:

  kernel/trace/trace_functions_graph.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-10 10:17:48 +01:00
Stoyan Gaydarov
8c5dfd2551 x86: BUG to BUG_ON changes
Impact: cleanup

Signed-off-by: Stoyan Gaydarov <stoyboyker@gmail.com>
LKML-Reference: <1236661850-8237-8-git-send-email-stoyboyker@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-10 09:55:18 +01:00
Dave Jones
129f8ae9b1 Revert "[CPUFREQ] Disable sysfs ui for p4-clockmod."
This reverts commit e088e4c9cd.

Removing the sysfs interface for p4-clockmod was flagged as a
regression in bug 12826.

Course of action:
 - Find out the remaining causes of overheating, and fix them
   if possible. ACPI should be doing the right thing automatically.
   If it isn't, we need to fix that.
 - mark p4-clockmod ui as deprecated
 - try again with the removal in six months.

It's not really feasible to printk about the deprecation, because
it needs to happen at all the sysfs entry points, which means adding
a lot of strcmp("p4-clockmod".. calls to the core, which.. bleuch.

Signed-off-by: Dave Jones <davej@redhat.com>
2009-03-09 15:07:33 -04:00
Jaswinder Singh Rajput
e255357764 x86: perf_counter cleanup
Remove unused variables and duplicate header file.

Signed-off-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-08 16:26:50 +01:00
Peter Zijlstra
184fe4ab1f x86: perf_counter cleanup
Use and actual unsigned long bitmap instead of casting our way around.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jaswinder Singh Rajput <jaswinder@kernel.org>
LKML-Reference: <1236508459.22914.3645.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-08 16:24:49 +01:00
Yinghai Lu
1f442d70c8 x86: remove smp_apply_quirks()/smp_checks()
Impact: cleanup and code size reduction on 64-bit

This code is only applied to Intel Pentium and AMD K7 32-bit cpus.

Move those checks to intel_init()/amd_init() for 32-bit
so 64-bit will not build this code.

Also change to use cpu_index check to see if we need to emit warning.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49B377D2.8030108@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-08 16:22:56 +01:00
Ingo Molnar
f0ef039851 Merge branch 'x86/core' into tracing/textedit
Conflicts:
	arch/x86/Kconfig
	block/blktrace.c
	kernel/irq/handle.c

Semantic conflict:
	kernel/trace/blktrace.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-06 16:45:01 +01:00
Ingo Molnar
caab36b593 Merge branch 'x86/mce2' into x86/core 2009-03-05 21:49:25 +01:00
Peter Zijlstra
b5e8acf66f perfcounters: IRQ and NMI support on AMD CPUs, fix
The BKGD suggests that counter width on AMD CPUs is 48 for all
existing models (it certainly is for mine).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-05 20:37:21 +01:00
Peter Zijlstra
b0f3f28e0f perfcounters: IRQ and NMI support on AMD CPUs
The below completes the K7+ performance counter support:

 - IRQ support
 - NMI support

KernelTop output works now as well.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jaswinder Singh Rajput <jaswinder@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1236273633.5187.286.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-05 18:25:16 +01:00
Dave Jones
36e8abf3ed [CPUFREQ] Prevent p4-clockmod from auto-binding to the ondemand governor.
The latency of p4-clockmod sucks so hard that scaling on a regular
basis with ondemand is a really bad idea.

Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Dave Jones <davej@redhat.com>
2009-03-05 00:16:26 -05:00
Ingo Molnar
73af76dfd1 x86, mce: fix build failure in arch/x86/kernel/cpu/mcheck/threshold.c
Impact: build fix

The APIC code rewrite in the x86 tree broke the x86/mce branch:

 arch/x86/kernel/cpu/mcheck/threshold.c: In function ‘mce_threshold_interrupt’:
 arch/x86/kernel/cpu/mcheck/threshold.c:24: error: implicit declaration of function ‘ack_APIC_irq’

Also tidy up the file a bit while at it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-04 11:48:28 +01:00
Ingo Molnar
91d75e209b Merge branch 'x86/core' into core/percpu 2009-03-04 02:29:19 +01:00
Ingo Molnar
8b0e5860cb Merge branches 'x86/apic', 'x86/cpu', 'x86/fixmap', 'x86/mm', 'x86/sched', 'x86/setup-lzma', 'x86/signal' and 'x86/urgent' into x86/core 2009-03-04 02:22:31 +01:00
Jaswinder Singh Rajput
a1ef58f442 x86: use pr_info in perf_counter.c
Impact: cleanup

using pr_info in perf_counter.c fixes various 80 characters warnings and
also indenting for conditional statement

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-02 11:31:44 +01:00
Jaswinder Singh Rajput
169e41eb7f x86: decent declarations in perf_counter.c
Impact: cleanup

making decent declrations for struct pmc_x86_ops and
fix checkpatch error:
 ERROR: Macros with complex values should be enclosed in parenthesis

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-02 11:31:06 +01:00
Jaswinder Singh Rajput
327f4387e3 x86: remove double copy of show_cpuinfo_core for 32 and 64 bit
Impact: unification

show_cpuinfo_core is identical for 32 and 64 bit and can be unified,
and CONFIG_X86_HT inherently depends on CONFIG_X86_SMP.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-02-28 19:26:33 -08:00
Jaswinder Singh Rajput
f87ad35d37 x86: AMD Support for perf_counter
Supported basic performance counter for AMD K7 and later:

$ perfstat -e 0,1,2,3,4,5,-1,-2,-3,-4,-5 ls > /dev/null

 Performance counter stats for 'ls':

      12.298610  task clock ticks     (msecs)

        3298477  CPU cycles           (events)
        1406354  instructions         (events)
         749035  cache references     (events)
          16939  cache misses         (events)
         100589  branches             (events)
          11159  branch misses        (events)
       7.627540  cpu clock ticks      (msecs)
      12.298610  task clock ticks     (msecs)
            500  pagefaults           (events)
              6  context switches     (events)
              3  CPU migrations       (events)

 Wall-clock time elapsed:     8.672290 msecs

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-28 10:38:32 +01:00
Jaswinder Singh Rajput
b56a3802dc x86: prepare perf_counter to add more cpus
Introduced  struct pmc_x86_ops to add more cpus.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-28 10:38:27 +01:00
Ingo Molnar
1b49061d40 Merge branch 'sched/clock' into tracing/ftrace
Conflicts:
	kernel/sched_clock.c
2009-02-27 08:35:19 +01:00
Ingo Molnar
ba1d755a36 fix warning in arch/x86/kernel/cpu/intel_cacheinfo.c
fix this warning:

  arch/x86/kernel/cpu/intel_cacheinfo.c:139: warning: ‘k8_nb_id’ defined but not used
  arch/x86/kernel/cpu/intel_cacheinfo.c:527: warning: ‘free_cache_attributes’ defined but not used
  arch/x86/kernel/cpu/intel_cacheinfo.c:538: warning: ‘detect_cache_attributes’ defined but not used

Unused variables in the !CONFIG_SYSCTL case.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-26 22:39:12 +01:00
Ingo Molnar
83ce400928 x86: set X86_FEATURE_TSC_RELIABLE
If the TSC is constant and non-stop, also set it reliable.

(We will turn this off in DMI quirks for multi-chassis systems)

The performance number on a 16-way Nehalem system running
32 tasks that context-switch between each other is significant:

   sched_clock_stable=0		sched_clock_stable=1
   ....................         ....................
   22.456925 million/sec        24.306972 million/sec   [+8.2%]

lmbench's "lat_ctx -s 0 2" goes from 0.63 microseconds to
0.59 microseconds - a 6.7% increase in context-switching
performance.

Perfstat of 1 million pipe context switches between two tasks:

 Performance counter stats for './pipe-test-1m':

       [before]           [after]
   ............      ............
   37621.421089      36436.848378    task clock ticks     (msecs)

              0                 0    CPU migrations       (events)
        2000274           2000189    context switches     (events)
            194               193    pagefaults           (events)
     8433799643        8171016416    CPU cycles           (events) -3.21%
     8370133368        8180999694    instructions         (events) -2.31%
        4158565           3895941    cache references     (events) -6.74%
          44312             46264    cache misses         (events)

    2349.287976       2279.362465    wall-time            (msecs)  -3.06%

The speedup comes straight from the reduction in the instruction
count. sched_clock_cpu() got simpler and the whole workload thus
executes faster.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-26 21:20:25 +01:00