linux-kernel - Re: [PATCH V4] perf: event preserve and create across cpu hotplug

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Date:   Tue, 18 Jun 2019 19:10:13 +0530
From:   Mukesh Ojha <mojha@...eaurora.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org,
        Raghavendra Rao Ananta <rananta@...eaurora.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>
Subject: Re: [PATCH V4] perf: event preserve and create across cpu hotplug


On 6/18/2019 5:53 PM, Peter Zijlstra wrote:
> On Tue, Jun 18, 2019 at 02:24:51PM +0530, Mukesh Ojha wrote:
>> Perf framework doesn't allow preserving CPU events across
>> CPU hotplugs. The events are scheduled out as and when the
>> CPU walks offline. Moreover, the framework also doesn't
>> allow the clients to create events on an offline CPU. As
>> a result, the clients have to keep on monitoring the CPU
>> state until it comes back online.
>>
>> Therefore,
> That's not a therefore. There's a distinct lack of rationale here. Why
> do you want this?

Thanks Peter for coming back on this.

Missed to send the coverletter,
https://lkml.org/lkml/2019/5/31/438
Will resend this with coverletter.

Btw,  This patch

is based on suggestion given by you on this
https://lkml.org/lkml/2018/2/16/763


Thanks.
Mukesh


Thanks.
Mukesh