linux-kernel - Re: [PATCH] perf/ftrace : Fix repetitious traces when specify a target task

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Date:   Tue, 10 Oct 2017 15:42:21 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "chengjian (D)" <cj.chengjian@...wei.com>
Cc:     mingo@...hat.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, linux-kernel@...r.kernel.org,
        xiexiuqi@...wei.com, huawei.libin@...wei.com,
        Steven Rostedt <rostedt@...dmis.org>,
        Jiri Olsa <jolsa@...nel.org>
Subject: Re: [PATCH] perf/ftrace : Fix repetitious traces when specify a
 target task

On Tue, Oct 10, 2017 at 08:18:13PM +0800, chengjian (D) wrote:

> and what cases should the events be delivered multiple times?


Task-A		Task-B		Task-C		Task-D

fd = sys_perf_event_open(B)			fd = sys_perf_event_open(C)

		wake_up_process(C)

Here A traces B, and D traces C. When B wakes C, we want both A and D to
get the event.