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Message-Id: <1386745860-21143-6-git-send-email-zheng.z.yan@intel.com>
Date: Wed, 11 Dec 2013 15:10:50 +0800
From: "Yan, Zheng" <zheng.z.yan@...el.com>
To: linux-kernel@...r.kernel.org
Cc: a.p.zijlstra@...llo.nl, eranian@...gle.com, andi@...stfloor.org,
"Yan, Zheng" <zheng.z.yan@...el.com>
Subject: [PATCH 05/15] perf, core: Optimize context switch callback invoking
From: "Yan, Zheng" <zheng.z.yan@...el.com>
So far only CPU pmu uses context switch callback and it is the
first registered pmu. So we can avoid iterating the whole pmu list.
Signed-off-by: Yan, Zheng <zheng.z.yan@...el.com>
---
kernel/events/core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index fc97ed6..c281265 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2373,6 +2373,10 @@ static void perf_pmu_sched_task(struct task_struct *prev,
perf_pmu_enable(pmu);
perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
+
+ /* so far only CPU pmu uses context switch callback */
+ if (++count >= __get_cpu_var(perf_sched_cb_usages))
+ break;
}
rcu_read_unlock();
@@ -6492,7 +6496,7 @@ got_cpu_context:
if (!pmu->event_idx)
pmu->event_idx = perf_event_idx_default;
- list_add_rcu(&pmu->entry, &pmus);
+ list_add_tail_rcu(&pmu->entry, &pmus);
ret = 0;
unlock:
mutex_unlock(&pmus_lock);
--
1.8.1.4
--
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