linux-kernel - Re: [PATCH] sched/core: Fix reset-on-fork from RT with uclamp

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Message-ID: <20200414162713.GA256619@google.com>
Date:   Tue, 14 Apr 2020 17:27:13 +0100
From:   Quentin Perret <qperret@...gle.com>
To:     Joel Fernandes <joel@...lfernandes.org>
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        ctheegal@...eaurora.org, dianders@...omium.org,
        patrick.bellasi@...bug.net, valentin.schneider@....com,
        qais.yousef@....com, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com
Subject: Re: [PATCH] sched/core: Fix reset-on-fork from RT with uclamp

On Tuesday 14 Apr 2020 at 12:21:28 (-0400), Joel Fernandes wrote:
> Shouldn't this be conditional on p->sched_reset_on_fork instead of deleting
> the code?

Right, it's not obvious from the diff, but this code _is_ conditional on
p->sched_reset_on_fork already. This is what the whole function looks
like with my patch applied:

---8<---
static void uclamp_fork(struct task_struct *p)
{
        enum uclamp_id clamp_id;

        for_each_clamp_id(clamp_id)
                p->uclamp[clamp_id].active = false;

        if (likely(!p->sched_reset_on_fork))
                return;

        for_each_clamp_id(clamp_id) {
                unsigned int clamp_value = uclamp_none(clamp_id);

                uclamp_se_set(&p->uclamp_req[clamp_id], clamp_value, false);
        }
}
--->8---

Thanks,
Quentin