sched_clock: Make it NMI safe

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Arjan complained about the suckyness of TSC on modern machines, and
asked if we could do something about that for PERF_SAMPLE_TIME.

Make cpu_clock() NMI safe by removing the spinlock and using
cmpxchg. This also makes it smaller and more robust.

Affects architectures that use HAVE_UNSTABLE_SCHED_CLOCK, i.e. IA64
and x86.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

...

This commit is contained in:

Peter Zijlstra 2009-09-18 20:14:01 +02:00 • committed by Ingo Molnar

parent cf450a7355

commit def0a9b257

2 changed files with 56 additions and 75 deletions

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9

kernel/perf_counter.c

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122

kernel/sched_clock.c

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