linux-kernel - Re: [PATCH] sched/uclamp: Fix getting unreasonable ucalmp

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Date:   Wed, 30 Jun 2021 20:05:37 +0800
From:   Xuewen Yan <xuewen.yan94@...il.com>
To:     Valentin Schneider <valentin.schneider@....com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Benjamin Segall <bsegall@...gle.com>,
        Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Patrick Bellasi <patrick.bellasi@...bug.net>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Quentin Perret <qperret@...gle.com>,
        Qais Yousef <qais.yousef@....com>
Subject: Re: [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq
 is idle

On Wed, Jun 30, 2021 at 7:31 PM Valentin Schneider
<valentin.schneider@....com> wrote:
>
> On 30/06/21 09:24, Xuewen Yan wrote:
> > On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider
> > <valentin.schneider@....com> wrote:
> >> +       min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value));
> >> +       max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value));
> >
> > Is it necessary to use max_t here? although it is not the main problem...
> >
>
> I got comparison warnings when using a regular max() - the RQ clamp values
> are unsigned int, whereas the local variable is unsigned long.

Yes，I miss the rq clamp value's type.

Thanks!
xuewen