linux-kernel - Re: [PATCH 0/4] perf: Fix the ctx->pmu for a hybrid system

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Date:   Thu, 17 Jun 2021 12:23:06 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     kan.liang@...ux.intel.com
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org, acme@...nel.org,
        mark.rutland@....com, ak@...ux.intel.com,
        alexander.shishkin@...ux.intel.com, namhyung@...nel.org,
        jolsa@...hat.com
Subject: Re: [PATCH 0/4] perf: Fix the ctx->pmu for a hybrid system

On Wed, Jun 16, 2021 at 11:55:30AM -0700, kan.liang@...ux.intel.com wrote:

> To fix the issue, the generic perf codes have to understand the
> supported CPU mask of a specific hybrid PMU. So it can update the
> ctx->pmu accordingly, when a task is scheduled on a CPU which has
> a different type of PMU from the previous CPU. The supported_cpus
> has to be moved to the struct pmu.

Urghh.. I so hate this :-/

I *did* point you to:

  https://lore.kernel.org/lkml/20181010104559.GO5728@hirez.programming.kicks-ass.net/

when you started this whole hybrid crud, and I think that's still the
correct thing to do.

Still, let me consider if there's a workable short-term cludge I hate
less.