linux-kernel - Re: [PATCH] blk-mq: add module parameter to not run block kworker on isolated CPUs

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Message-ID: <ZSk2wNH4KIR4rR+N@fedora>
Date:   Fri, 13 Oct 2023 20:23:28 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     Tejun Heo <tj@...nel.org>, Jens Axboe <axboe@...nel.dk>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Juri Lelli <juri.lelli@...hat.com>,
        Andrew Theurer <atheurer@...hat.com>,
        Joe Mario <jmario@...hat.com>, Sebastian Jug <sejug@...hat.com>
Subject: Re: [PATCH] blk-mq: add module parameter to not run block kworker on
 isolated CPUs

On Fri, Oct 13, 2023 at 01:26:08PM +0200, Frederic Weisbecker wrote:
> On Tue, Oct 10, 2023 at 08:45:44AM -1000, Tejun Heo wrote:
> > > +static bool respect_cpu_isolation;
> > > +module_param(respect_cpu_isolation, bool, 0444);
> > > +MODULE_PARM_DESC(respect_cpu_isolation,
> > > +		"Don't schedule blk-mq worker on isolated CPUs passed in "
> > > +		"isolcpus= or nohz_full=. User need to guarantee to not run "
> > > +		"block IO on isolated CPUs (default: false)");
> > 
> > Any chance we can centralize these? It's no fun to try to hunt down module
> > params to opt in different subsystems and the housekeeping interface does
> > have some provisions for selecting different parts. I'd much prefer to see
> > these settings to be collected into a central place.
> 
> Do we need this parameter in the first place? Shouldn't we avoid scheduling
> blk-mq worker on isolated CPUs in any case?

Yeah, I think this parameter isn't necessary, will remove it in V2.


Thanks,
Ming