Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d7b629a3 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090520102553.237504544@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c44d70a3

include/linux/perf_counter.h

+0 −1
Original line number Diff line number Diff line
@@ -508,7 +508,6 @@ struct perf_counter_context { 
	int			nr_counters;

	int			nr_active;

	int			is_active;

	int			rr_allowed;

	struct task_struct	*task;



	/*

kernel/perf_counter.c

+5 −10
Original line number Diff line number Diff line
@@ -1120,7 +1120,6 @@ 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);



	perf_counter_cpu_sched_in(cpuctx, 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);

}