summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorMark Rutland <mark.rutland@arm.com>2014-02-10 17:44:19 +0000
committerIngo Molnar <mingo@kernel.org>2014-02-27 12:43:24 +0100
commitfdded676c3ef680bf1abc415d307d7e69a6768d1 (patch)
tree1e279e330e37d4ef5e096872512f902792334959
parent9e3170411ed171a126f4dca1672012a33efe59e5 (diff)
perf: Remove redundant PMU assignment
Currently perf_branch_stack_sched_in iterates over the set of pmus, checks that each pmu has a flush_branch_stack callback, then overwrites the pmu before calling the callback. This is either redundant or broken. In systems with a single hw pmu, pmu == cpuctx->ctx.pmu, and thus the assignment is redundant. In systems with multiple hw pmus (i.e. multiple pmus with task_ctx_nr == perf_hw_context) the pmus share the same perf_cpu_context. Thus the assignment can cause one of the pmus to flush its branch stack repeatedly rather than causing each of the pmus to flush their branch stacks. Worse still, if only some pmus have the callback the assignment can result in a branch to NULL. This patch removes the redundant assignment. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/r/1392054264-23570-3-git-send-email-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/events/core.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 425159882a6f..823a53d72d6a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2582,8 +2582,6 @@ static void perf_branch_stack_sched_in(struct task_struct *prev,
if (cpuctx->ctx.nr_branch_stack > 0
&& pmu->flush_branch_stack) {
- pmu = cpuctx->ctx.pmu;
-
perf_ctx_lock(cpuctx, cpuctx->task_ctx);
perf_pmu_disable(pmu);