Ingo provided me a config that fails to compile with:
arch/x86/built-in.o: In function
`arch_trigger_all_cpu_backtrace': (.text+0x17e78): undefined
reference to `apic' make: *** [.tmp_vmlinux1] Error 1
I realized I changed the compile behaviour of the nmi code by
not wrapping it with CONFIG_LOCAL_APIC. To fix this I add a
compile check for ARCH_HAS_NMI_WATCHDOG around
arch_trigger_all_cpu_backtrace.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: a.p.zijlstra@chello.nl
Cc: gorcunov@gmail.com
Cc: aris@redhat.com
LKML-Reference: <1266548212-24243-1-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The original patch was x86_64 centric. Changed the code to make
it less so.
ested by building and running on a powerpc.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: peterz@infradead.org
Cc: gorcunov@gmail.com
Cc: aris@redhat.com
LKML-Reference: <1266013161-31197-2-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This is a new generic nmi_watchdog implementation using the perf
events infrastructure as suggested by Ingo.
The implementation is simple, just create an in-kernel perf
event and register an overflow handler to check for cpu lockups.
I created a generic implementation that lives in kernel/ and
the hardware specific part that for now lives in arch/x86.
This approach has a number of advantages:
- It simplifies the x86 PMU implementation in the long run,
in that it removes the hardcoded low-level PMU implementation
that was the NMI watchdog before.
- It allows new NMI watchdog features to be added in a central
place.
- It allows other architectures to enable the NMI watchdog,
as long as they have perf events (that provide NMIs)
implemented.
- It also allows for more graceful co-existence of existing
perf events apps and the NMI watchdog - before these changes
the relationship was exclusive. (The NMI watchdog will 'spend'
a perf event when enabled. In later iterations we might be
able to piggyback from an existing NMI event without having
to allocate a hardware event for the NMI watchdog - turning
this into a no-hardware-cost feature.)
As for compatibility, we'll keep the old NMI watchdog code as
well until the new one can 100% replace it on all CPUs, old and
new alike. That might take some time as the NMI watchdog has
been ported to many CPU models.
I have done light testing to make sure the framework works
correctly and it does.
v2: Set the correct timeout values based on the old nmi
watchdog
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: gorcunov@gmail.com
Cc: aris@redhat.com
Cc: peterz@infradead.org
LKML-Reference: <1265424425-31562-3-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
