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From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org, acme@kernel.org, mark.rutland@arm.com,
	alexander.shishkin@linux.intel.com, jolsa@redhat.com,
	namhyung@kernel.org
Cc: linux-kernel@vger.kernel.org, eranian@google.com,
	ak@linux.intel.com, peterz@infradead.org
Subject: [PATCH v2 4/4] perf: Tweak perf_event_attr::exclusive semantics
Date: Thu, 29 Oct 2020 17:27:23 +0100
Message-ID: <20201029162902.105962225@infradead.org> (raw)
In-Reply-To: <20201029162719.519685265@infradead.org>

Currently perf_event_attr::exclusive can be used to ensure an
event(group) is the sole group scheduled on the PMU. One consequence
is that when you have a pinned event (say the watchdog) you can no
longer have regular exclusive event(group)s.

Inspired by the fact that !pinned events are considered less strict,
allow !pinned,exclusive events to share the PMU with pinned,!exclusive
events.

Pinned,exclusive is still fully exclusive.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/events/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2637,7 +2637,7 @@ static int group_can_go_on(struct perf_e
 	 * If this group is exclusive and there are already
 	 * events on the CPU, it can't go on.
 	 */
-	if (event->attr.exclusive && cpuctx->active_oncpu)
+	if (event->attr.exclusive && !list_empty(get_event_list(event)))
 		return 0;
 	/*
 	 * Otherwise, try to add it if all previous groups were able



  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-29 16:27 [PATCH v2 0/4] perf: Fix perf_event_attr::exclusive rotation Peter Zijlstra
2020-10-29 16:27 ` [PATCH v2 1/4] perf: Simplify group_sched_out() Peter Zijlstra
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra
2020-10-29 16:27 ` [PATCH v2 2/4] perf: Simplify group_sched_in() Peter Zijlstra
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra
2020-10-29 16:27 ` [PATCH v2 3/4] perf: Fix event multiplexing for exclusive groups Peter Zijlstra
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra
2020-10-29 16:27 ` Peter Zijlstra [this message]
2020-11-10 12:45   ` [tip: perf/urgent] perf: Tweak perf_event_attr::exclusive semantics tip-bot2 for Peter Zijlstra
2020-10-31 23:44 ` [PATCH v2 0/4] perf: Fix perf_event_attr::exclusive rotation Jiri Olsa
2020-11-02  3:52   ` Andi Kleen
2020-11-02 14:16     ` Peter Zijlstra
2020-11-03  2:41       ` Andi Kleen
2020-11-09 11:48         ` Peter Zijlstra

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