linux-kernel - Re: [RFC][PATCH] perf: Rewrite core context handling

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Date:   Fri, 12 Oct 2018 13:54:20 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Song Liu <songliubraving@...com>, Ingo Molnar <mingo@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "acme@...nel.org" <acme@...nel.org>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "jolsa@...hat.com" <jolsa@...hat.com>,
        "eranian@...gle.com" <eranian@...gle.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "megha.dey@...el.com" <megha.dey@...el.com>,
        "frederic@...nel.org" <frederic@...nel.org>
Subject: Re: [RFC][PATCH] perf: Rewrite core context handling

On Fri, Oct 12, 2018 at 10:04:36AM +0300, Alexey Budankov wrote:
> On 11.10.2018 12:29, Peter Zijlstra wrote:
> > On Thu, Oct 11, 2018 at 07:50:23AM +0000, Song Liu wrote:
> >> Or step back a little... I see two big changes:
> >>
> >> 1. struct perf_ctx_context is now per cpu (instead of per pmu per cpu);
> >> 2. one perf_event_ctxp per task_struct (instead of 2).  
> > 
> > Correct, we reduce to 1 cpu context and 1 task context at all times.
> > This in fact simplifies quite a bit of things.
> 
> And what is currently missing is 
> some markup of the per cpu event list into per pmu sublists and 
> capability to rotate or not rotate the sublists independently, 
> right?

Yes, that is what the new perf_event_pmu_context is. That tracks the per
pmu sublist state.