Commit-ID: d7b629a34fc4134a43c730b5f0197855dc4948d0
Gitweb: http://git.kernel.org/tip/d7b629a34fc4134a43c730b5f0197855dc4948d0
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Wed, 20 May 2009 12:21:19 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 20 May 2009 12:43:32 +0200
perf_counter: Solve the rotate_ctx vs inherit race differently
Instead of disabling RR scheduling of the counters, use a different list
that does not get rotated to iterate the counters on inheritance.
[ Impact: cleanup, optimization ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Cc: John Kacur <jkacur@xxxxxxxxxx>
LKML-Reference: <20090520102553.237504544@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
include/linux/perf_counter.h | 1 -
kernel/perf_counter.c | 15 +++++----------
2 files changed, 5 insertions(+), 11 deletions(-)
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 13cb2fb..c8c1dfc 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -508,7 +508,6 @@ struct perf_counter_context {
int nr_counters;
int nr_active;
int is_active;
- int rr_allowed;
struct task_struct *task;
/*
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 4d8f973..64113e6 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1120,8 +1120,7 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu)
__perf_counter_task_sched_out(ctx);
rotate_ctx(&cpuctx->ctx);
- if (ctx->rr_allowed)
- rotate_ctx(ctx);
+ rotate_ctx(ctx);
perf_counter_cpu_sched_in(cpuctx, cpu);
perf_counter_task_sched_in(curr, cpu);
@@ -3109,7 +3108,6 @@ __perf_counter_init_context(struct perf_counter_context *ctx,
mutex_init(&ctx->mutex);
INIT_LIST_HEAD(&ctx->counter_list);
INIT_LIST_HEAD(&ctx->event_list);
- ctx->rr_allowed = 1;
ctx->task = task;
}
@@ -3350,14 +3348,14 @@ void perf_counter_init_task(struct task_struct *child)
*/
mutex_lock(&parent_ctx->mutex);
- parent_ctx->rr_allowed = 0;
- barrier(); /* irqs */
-
/*
* We dont have to disable NMIs - we are only looking at
* the list, not manipulating it:
*/
- list_for_each_entry(counter, &parent_ctx->counter_list, list_entry) {
+ list_for_each_entry_rcu(counter, &parent_ctx->event_list, event_entry) {
+ if (counter != counter->group_leader)
+ continue;
+
if (!counter->hw_event.inherit)
continue;
@@ -3366,9 +3364,6 @@ void perf_counter_init_task(struct task_struct *child)
break;
}
- barrier(); /* irqs */
- parent_ctx->rr_allowed = 1;
-
mutex_unlock(&parent_ctx->mutex);
}
--
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