sched_clock: Make it NMI safe
authorPeter Zijlstra <a.p.zijlstra@chello.nl>
Fri, 18 Sep 2009 18:14:01 +0000 (20:14 +0200)
committerIngo Molnar <mingo@elte.hu>
Fri, 18 Sep 2009 18:47:30 +0000 (20:47 +0200)
commitdef0a9b2573e00ab0b486cb5382625203ab4c4a6
tree1e3086fc320c244297b5b63cce47065bcfb71e8c
parentcf450a7355a116af793998c118a6bcf7f5a8367e
sched_clock: Make it NMI safe

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>
kernel/perf_counter.c
kernel/sched_clock.c