From: Christoph Hellwig <hch@infradead.org>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: Christoph Hellwig <hch@infradead.org>,
axboe@kernel.dk, bigeasy@linutronix.de, tglx@linutronix.de,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH] blk-mq: make synchronous hw_queue runs RT friendly
Date: Tue, 14 Dec 2021 00:08:05 -0800 [thread overview]
Message-ID: <YbhQ5b2qZN0Jpk5i@infradead.org> (raw)
In-Reply-To: <20211213190529.j54qikq7mk5zuc3o@offworld>
On Mon, Dec 13, 2021 at 11:05:29AM -0800, Davidlohr Bueso wrote:
> On Mon, 13 Dec 2021, Christoph Hellwig wrote:
> > But more importantly: why isn't migrate_disable/enable doing the right
> > thing for !PREEMPT_RT to avoid this mess?
>
> Please see Peter's description of the situation in af449901b84.
That explains why migrate_disable is a bad idea in PREEMPT_RT, not why it
can't do something sensible for !PREEMPT_RT…
>
> While I'm not at all a fan of sprinkling migrate_disabling around code,
> I didn't want to add any overhead for the common case. If this, however,
> were not an issue (if most cases are async runs, for example) the ideal
> solution I think would be to just pin current to the hctx->cpumask.
sync running is the performance case.
prev parent reply other threads:[~2021-12-14 8:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-13 5:44 [PATCH] blk-mq: make synchronous hw_queue runs RT friendly Davidlohr Bueso
2021-12-13 13:07 ` Christoph Hellwig
2021-12-13 13:52 ` Sebastian Andrzej Siewior
2021-12-13 19:05 ` Davidlohr Bueso
2021-12-14 8:08 ` Christoph Hellwig [this message]
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