From: Bart Van Assche <bvanassche@acm.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Hannes Reinecke <hare@suse.de>,
John Garry <john.garry@huawei.com>,
David Jeffery <djeffery@redhat.com>
Subject: Re: [PATCH V5 3/4] blk-mq: clear stale request in tags->rq[] before freeing one request pool
Date: Thu, 6 May 2021 20:16:25 -0700 [thread overview]
Message-ID: <a2a7e66b-68e8-6468-2add-19ffbe096ed9@acm.org> (raw)
In-Reply-To: <YJSggHqgMFfWIALu@T590>
On 5/6/21 7:05 PM, Ming Lei wrote:
> Putting the lock pair after clearing rq mapping should work, but not see
> any benefit: not very readable, and memory barrier knowledge is required for
> understanding its correctness(cmpxchg has to be completed before unlock), ...,
> so is it better idea to move lock pair after clearing rq mapping?
It depends on how much time will be spent inside
blk_mq_clear_rq_mapping(). If the time spent in the nested loop in
blk_mq_clear_rq_mapping() would be significant then the proposed change
will help to reduce interrupt latency in blk_mq_find_and_get_req().
Thanks,
Bart.
next prev parent reply other threads:[~2021-05-07 3:16 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 14:58 [PATCH V5 0/4] blk-mq: fix request UAF related with iterating over tagset requests Ming Lei
2021-05-05 14:58 ` [PATCH V5 1/4] block: avoid double io accounting for flush request Ming Lei
2021-05-06 6:44 ` Christoph Hellwig
2021-05-05 14:58 ` [PATCH V5 2/4] blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter Ming Lei
2021-05-06 6:54 ` Christoph Hellwig
2021-05-06 7:30 ` Ming Lei
2021-05-05 14:58 ` [PATCH V5 3/4] blk-mq: clear stale request in tags->rq[] before freeing one request pool Ming Lei
2021-05-06 7:12 ` Christoph Hellwig
2021-05-06 7:34 ` Ming Lei
2021-05-06 12:18 ` Christoph Hellwig
2021-05-06 13:38 ` Ming Lei
2021-05-07 6:57 ` Christoph Hellwig
2021-05-07 7:30 ` Ming Lei
2021-05-06 14:51 ` Bart Van Assche
2021-05-07 0:11 ` Ming Lei
2021-05-07 1:10 ` Bart Van Assche
2021-05-07 2:05 ` Ming Lei
2021-05-07 3:16 ` Bart Van Assche [this message]
2021-05-07 6:31 ` Ming Lei
2021-05-07 6:52 ` Christoph Hellwig
2021-05-08 2:02 ` Bart Van Assche
2021-05-06 15:02 ` Bart Van Assche
2021-05-07 0:13 ` Ming Lei
2021-05-07 1:11 ` Bart Van Assche
2021-05-07 2:06 ` Ming Lei
2021-05-05 14:58 ` [PATCH V5 4/4] blk-mq: clearing flush request reference in tags->rqs[] Ming Lei
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=a2a7e66b-68e8-6468-2add-19ffbe096ed9@acm.org \
--to=bvanassche@acm.org \
--cc=axboe@kernel.dk \
--cc=djeffery@redhat.com \
--cc=hare@suse.de \
--cc=hch@infradead.org \
--cc=john.garry@huawei.com \
--cc=linux-block@vger.kernel.org \
--cc=ming.lei@redhat.com \
/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;
as well as URLs for NNTP newsgroup(s).