Re: attr inherit vs inherit_stat
On Tue, 4 Sep 2012, Namhyung Kim wrote: AFAIK the inherit field determines whether the event is inherited to a child process/thread. The inherit_stat is only meaningful when the inherit field is also set and it'll preserve (saved) event counts between context switch of the inherited processes/threads. Thank you for taking the time to answer! I'm still trying to construct a test case that shows the difference but I'm failing. Aren't the stats *always* saved on context switch? Does this affect what happens when you read the perf_event fd in the inherited threads, or only from the master thread? What is the expected behavior if you set inherit_thread but do not set inherit? Thanks for any clarifications you can provide, Vince -- To unsubscribe from this list: send the line unsubscribe linux-perf-users in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: attr inherit vs inherit_stat
(Adding peterz in case he has a time to answer) On Thu, 6 Sep 2012 11:19:21 -0400, Vince Weaver wrote: On Tue, 4 Sep 2012, Namhyung Kim wrote: AFAIK the inherit field determines whether the event is inherited to a child process/thread. The inherit_stat is only meaningful when the inherit field is also set and it'll preserve (saved) event counts between context switch of the inherited processes/threads. Thank you for taking the time to answer! I'm still trying to construct a test case that shows the difference but I'm failing. Please note that my understanding of perf core code is not firm enough so there might be some mistakes. ;-) Aren't the stats *always* saved on context switch? If both of them are cloned from the same parent event context and there's no event added in the meantime. Please see perf_event_context_sched_out() calling perf_event_sync_stat. Does this affect what happens when you read the perf_event fd in the inherited threads, or only from the master thread? It might. But I guess the master thread doesn't get affected from that. What is the expected behavior if you set inherit_thread but do not set inherit? You meant inherit_stat, right? If so, it looks it'd be a nop since there's no inherited events. Maybe the perf tools can be changed to warn about that. Thanks, Namhyung -- To unsubscribe from this list: send the line unsubscribe linux-perf-users in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: attr inherit vs inherit_stat
On Tue, 7 Aug 2012 15:47:32 -0400, Vince Weaver wrote: Hello Hello Vince, I'm trying to figure out the difference between the inherit and inherit_stat bitfields in the perf_event_attr structure. Both seem to have similar functionality, and the code in core.c is hard to follow. Does anyone have any idea? AFAIK the inherit field determines whether the event is inherited to a child process/thread. The inherit_stat is only meaningful when the inherit field is also set and it'll preserve (saved) event counts between context switch of the inherited processes/threads. Thanks, Namhyung -- To unsubscribe from this list: send the line unsubscribe linux-perf-users in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
attr inherit vs inherit_stat
Hello I'm trying to figure out the difference between the inherit and inherit_stat bitfields in the perf_event_attr structure. Both seem to have similar functionality, and the code in core.c is hard to follow. Does anyone have any idea? Thanks, Vince vweav...@eecs.utk.edu -- To unsubscribe from this list: send the line unsubscribe linux-perf-users in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
