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authorPeter Zijlstra <peterz@infradead.org>2017-08-03 16:42:09 +0300
committerIngo Molnar <mingo@kernel.org>2017-08-10 13:01:09 +0300
commit9b231d9f47c6114d317ce28cff92a74ad80547f5 (patch)
tree97e34b1a82a56ab28046055a0c4dfc6d288c228f /tools/build
parentbfe334924ccd9f4a53f30240c03cf2f43f5b2df1 (diff)
downloadlinux-9b231d9f47c6114d317ce28cff92a74ad80547f5.tar.xz
perf/core: Fix time on IOC_ENABLE
Vince reported that when we do IOC_ENABLE/IOC_DISABLE while the task is SIGSTOP'ed state the timestamps go wobbly. It turns out we indeed fail to correctly account time while in 'OFF' state and doing IOC_ENABLE without getting scheduled in exposes the problem. Further thinking about this problem, it occurred to me that we can suffer a similar fate when we migrate an uncore event between CPUs. The perf_event_install() on the 'new' CPU will do add_event_to_ctx() which will reset all the time stamp, resulting in a subsequent update_event_times() to overwrite the total_time_* fields with smaller values. Reported-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
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