From 7995888fcb0246543ee8027bf2835a250ba8c925 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 17 Dec 2008 08:54:56 +0100 Subject: [PATCH] perfcounters: tweak group scheduling Impact: schedule in groups atomically If there are multiple groups in a task, make sure they are scheduled in and out atomically. Signed-off-by: Ingo Molnar --- kernel/perf_counter.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index aab6c123b02c..f8a4d9a5d5d3 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -367,21 +367,26 @@ counter_sched_in(struct perf_counter *counter, ctx->nr_active++; } -static void +static int group_sched_in(struct perf_counter *group_counter, struct perf_cpu_context *cpuctx, struct perf_counter_context *ctx, int cpu) { struct perf_counter *counter; + int was_group = 0; counter_sched_in(group_counter, cpuctx, ctx, cpu); /* * Schedule in siblings as one group (if any): */ - list_for_each_entry(counter, &group_counter->sibling_list, list_entry) + list_for_each_entry(counter, &group_counter->sibling_list, list_entry) { counter_sched_in(counter, cpuctx, ctx, cpu); + was_group = 1; + } + + return was_group; } /* @@ -416,7 +421,12 @@ void perf_counter_task_sched_in(struct task_struct *task, int cpu) if (counter->cpu != -1 && counter->cpu != cpu) continue; - group_sched_in(counter, cpuctx, ctx, cpu); + /* + * If we scheduled in a group atomically and + * exclusively, break out: + */ + if (group_sched_in(counter, cpuctx, ctx, cpu)) + break; } spin_unlock(&ctx->lock); -- 2.20.1