Messages in this thread | | | Date | Thu, 03 Jul 2014 13:44:48 +0800 | From | "Yan, Zheng" <> | Subject | Re: [PATCH V4 03/16] perf, x86: use context switch callback to flush LBR stack |
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On 07/02/2014 05:06 PM, Peter Zijlstra wrote: > On Mon, Jun 30, 2014 at 04:50:40PM +0800, Yan, Zheng wrote: >> @@ -185,6 +185,23 @@ void intel_pmu_lbr_enable(struct perf_event *event) >> return; >> >> /* >> + * It is necessary to flush the stack on context switch. This happens >> + * when the branch stack does not tag its entries with the pid of the >> + * current task. > > Did you mean to say: "This happens _because_ the branch stack does not > tag its entries with the pid of the current task." ?
yes. The comment is copied from comments of perf_branch_stack_sched_in()
Regards Yan, Zheng
> >> + */ >> + if (sched_in) { >> + intel_pmu_lbr_reset(); >> + cpuc->lbr_context = ctx; >> + } >> +}
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