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Commit e2864173 authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

perf: Round robin flexible groups of events using list_rotate_left() 



This is more proper that doing it through a list_for_each_entry()
that breaks after the first entry.

v2: Don't rotate pinned groups as its not needed to time share
them.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
parent 5908cdc8

kernel/perf_event.c

+4 −13
Original line number Diff line number Diff line
@@ -1454,25 +1454,16 @@ static void perf_ctx_adjust_freq(struct perf_event_context *ctx) 
 */

static void rotate_ctx(struct perf_event_context *ctx)

{

	struct perf_event *event;



	if (!ctx->nr_events)

		return;



	raw_spin_lock(&ctx->lock);

	/*

	 * Rotate the first entry last (works just fine for group events too):

	 */



	/* Rotate the first entry last of non-pinned groups */

	perf_disable();

	list_for_each_entry(event, &ctx->pinned_groups, group_entry) {

		list_move_tail(&event->group_entry, &ctx->pinned_groups);

		break;

	}



	list_for_each_entry(event, &ctx->flexible_groups, group_entry) {

		list_move_tail(&event->group_entry, &ctx->flexible_groups);

		break;

	}

	list_rotate_left(&ctx->flexible_groups);



	perf_enable();



	raw_spin_unlock(&ctx->lock);