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

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Message-ID: <YwzP+AFWCx4Ni/kx@hirez.programming.kicks-ass.net>
Date:   Mon, 29 Aug 2022 16:40:56 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ravi Bangoria <ravi.bangoria@....com>
Cc:     acme@...nel.org, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org, songliubraving@...com,
        eranian@...gle.com, ak@...ux.intel.com, mark.rutland@....com,
        frederic@...nel.org, maddy@...ux.ibm.com, irogers@...gle.com,
        will@...nel.org, robh@...nel.org, mingo@...hat.com,
        catalin.marinas@....com, linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        sandipan.das@....com, ananth.narayan@....com, kim.phillips@....com,
        santosh.shukla@....com
Subject: Re: [PATCH] perf: Rewrite core context handling

On Mon, Aug 29, 2022 at 02:04:33PM +0200, Peter Zijlstra wrote:
> On Mon, Aug 29, 2022 at 05:03:47PM +0530, Ravi Bangoria wrote:
> > @@ -12598,6 +12590,7 @@ EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
> >  
> >  void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
> >  {
> > +#if 0 // XXX buggered - cpu hotplug, who cares
> >  	struct perf_event_context *src_ctx;
> >  	struct perf_event_context *dst_ctx;
> >  	struct perf_event *event, *tmp;
> > @@ -12658,6 +12651,7 @@ void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
> >  	}
> >  	mutex_unlock(&dst_ctx->mutex);
> >  	mutex_unlock(&src_ctx->mutex);
> > +#endif
> >  }
> >  EXPORT_SYMBOL_GPL(perf_pmu_migrate_context);
> >  
> 
> Note to self; fix this :-) I'll see if I have time for that later today.

Urgh, while going through that it appears the whole refcounting thing
isn't fully done either.