Commit 5a158c3c authored Nov 04, 2014 by Yan, Zheng Committed by Ingo Molnar Feb 18, 2015

perf: Always switch pmu specific data during context switch



If two tasks were both forked from the same parent task, Events in
their perf task contexts can be the same. Perf core may leave out
switching the perf event contexts.

Previous patch inroduces pmu specific data. The data is for saving
the LBR stack, it is task specific. So we need to switch the data
even when context switch is optimized out.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: eranian@google.com
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1415156173-10035-7-git-send-email-kan.liang@intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 4af57ef2

kernel/events/core.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -2562,6 +2562,9 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
		next->perf_event_ctxp[ctxn] = ctx;
		ctx->task = next;
		next_ctx->task = task;

		swap(ctx->task_ctx_data, next_ctx->task_ctx_data);

		do_switch = 0;

		perf_event_sync_stat(ctx, next_ctx);

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