From: Ming Lei <ming.lei@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2] blk-mq: Don't disable preemption around __blk_mq_run_hw_queue().
Date: Wed, 22 Jun 2022 16:35:46 +0800 [thread overview]
Message-ID: <YrLUYvEaKeW6Mmfd@T590> (raw)
In-Reply-To: <YrLSEiNvagKJaDs5@linutronix.de>
On Wed, Jun 22, 2022 at 10:25:54AM +0200, Sebastian Andrzej Siewior wrote:
> __blk_mq_delay_run_hw_queue() disables preemption to get a stable
> current CPU number and then invokes __blk_mq_run_hw_queue() if the CPU
> number is part the mask.
>
> __blk_mq_run_hw_queue() acquires a spin_lock_t which is a sleeping lock
> on PREEMPT_RT and can't be acquired with disabled preemption.
>
> It is not required for correctness to invoke __blk_mq_run_hw_queue() on
> a CPU matching hctx->cpumask. Both (async and direct requests) can run
> on a CPU not matching hctx->cpumask.
>
> The CPU mask without disabling preemption and invoking
> __blk_mq_run_hw_queue().
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Looks fine:
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Thanks,
Ming
next prev parent reply other threads:[~2022-06-22 8:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-21 7:39 [PATCH REPOST] blk-mq: Don't disable preemption around __blk_mq_run_hw_queue() Sebastian Andrzej Siewior
2022-06-21 7:56 ` Ming Lei
2022-06-22 8:25 ` [PATCH v2] " Sebastian Andrzej Siewior
2022-06-22 8:35 ` Ming Lei [this message]
2022-06-22 17:46 ` Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YrLUYvEaKeW6Mmfd@T590 \
--to=ming.lei@redhat.com \
--cc=axboe@kernel.dk \
--cc=bigeasy@linutronix.de \
--cc=linux-block@vger.kernel.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox