Re: [RFC] [PATCH] perf, x86: Add PERF_COUNT_HW_NMI_WATCHDOG event

From: Peter Zijlstra
Date: Fri Apr 01 2011 - 06:54:02 EST


On Fri, 2011-04-01 at 01:16 +0400, Cyrill Gorcunov wrote:
> Because of Netburst HW restriction we can't move events arbitrary
> between counters and this makes 'perf top' unable to run if nmi-watchdog
> is running (since both uses PERF_COUNT_HW_CPU_CYCLES but such event is
> bound to run on a few counters only). So as a workaround we could count that named
> non-sleeping ticks (as oprofile does) and both perf top and nmi-watchdog would co-exsist
> without conflicts but kernel needs to know about such specifics -- so PERF_COUNT_HW_NMI_WATCHDOG
> event is introduced. This event is an alias of PERF_COUNT_HW_CPU_CYCLES for non-P4 x86
> architecture so nothing much changed I think.
>
> Please review, I might be missing something. Also comments on idea is quite welcome since
> it touches ABI part.


> arch/x86/kernel/cpu/perf_event_amd.c | 1 +
> arch/x86/kernel/cpu/perf_event_intel.c | 1 +
> arch/x86/kernel/cpu/perf_event_p4.c | 15 +++++++++++++++
> arch/x86/kernel/cpu/perf_event_p6.c | 1 +
> include/linux/perf_event.h | 1 +
> kernel/watchdog.c | 2 +-
> 6 files changed, 20 insertions(+), 1 deletions(-)

is x86 the only arch using the watchdog things?
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