linux-kernel - Re: [PATCH] perf/core: fix multiplexing event scheduling issue

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Message-ID: <20191023152920.GG19358@hirez.programming.kicks-ass.net>
Date:   Wed, 23 Oct 2019 17:29:20 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Stephane Eranian <eranian@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, mingo@...e.hu,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Jiri Olsa <jolsa@...hat.com>,
        "Liang, Kan" <kan.liang@...el.com>,
        Song Liu <songliubraving@...com>,
        Ian Rogers <irogers@...gle.com>
Subject: Re: [PATCH] perf/core: fix multiplexing event scheduling issue

On Wed, Oct 23, 2019 at 11:37:57AM +0200, Peter Zijlstra wrote:
> Further, since we set it on reschedule, I propose you change the above
> like:
> 
> 	if (ctx->rotate_necessary) {
> 		int type = get_event_type(event);
> 		/*
> 		 * comment..
> 		 */
> 		if (type & EVENT_PINNED)
> 			type |= EVENT_FLEXIBLE;
> +		/*
> +		 * Will be reset by ctx_resched()'s flexible_sched_in().
> +		 */
> +		ctx->rotate_necessary = 0;
> 		ctx_resched(cpuctx, cpuctx->task_ctx, type);
> 	}

n/m, that is already done through ctx_sched_out().