From: Tejun Heo <tj@kernel.org>
To: Shaohua Li <shli@kernel.org>
Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org,
kernel-team@fb.com, lizefan@huawei.com, hannes@cmpxchg.org,
cgroups@vger.kernel.org, guro@fb.com
Subject: Re: [PATCH 7/7] blk-throtl: don't throttle the same IO multiple times
Date: Mon, 13 Nov 2017 11:58:54 -0800 [thread overview]
Message-ID: <20171113195854.GJ983427@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20171113195413.b5lzqem2pt2bg4oe@kernel.org>
Hello,
On Mon, Nov 13, 2017 at 11:54:13AM -0800, Shaohua Li wrote:
> I'm not sure how you are going to make this correct. The mechanism is very
> fragile. So for example, 'q->make_request_fn(q, bio)' could just queue the bio
> somewhere and handle in other context (both dm and md do this). The bio will be
> called again with generic_make_request. In this case, the second time shouldn't
> throttle the bio. The bio could be called again with generic_make_request but
> with bdev changed. In this case, the second time should throttle the bio
> (against the new bdev). There are a lot of different usages of bio. I'd rather
> not depend on generic_make_request dispatches new bio immediately. That's why I
> add a bdev in my patch.
I see. Yeah, that makes sense. The cloned bios may get queued to a
different request_queue asynchronously and without remembering the
last queue, you can't tell whether it's a new queue or not. I'll drop
this one and test with your patch.
Thanks.
--
tejun
next prev parent reply other threads:[~2017-11-13 19:58 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-12 22:26 [PATCHSET] blkcg: basic accounting and throttling fixes Tejun Heo
2017-11-12 22:26 ` [PATCH 1/7] blkcg: relocate __blkg_release_rcu() Tejun Heo
2017-11-14 23:12 ` Shaohua Li
2017-11-12 22:26 ` [PATCH 2/7] blkcg: use percpu_ref for blkcg_gq->refcnt Tejun Heo
2017-11-14 23:12 ` Shaohua Li
2017-11-12 22:26 ` [PATCH 3/7] blkcg: associate a request with its blkcg_gq instead of request_list Tejun Heo
2017-11-13 20:15 ` [PATCH v2 " Tejun Heo
2017-11-14 23:17 ` Shaohua Li
2017-11-15 17:11 ` Tejun Heo
2017-11-12 22:26 ` [PATCH 4/7] blkcg: refactor blkcg_gq lookup and creation in blkcg_bio_issue_check() Tejun Heo
2017-11-14 23:18 ` Shaohua Li
2017-11-12 22:26 ` [PATCH 5/7] blkcg: associate blk-mq requests with the matching blkcg_gqs Tejun Heo
2017-11-12 22:26 ` [PATCH 6/7] blkcg: account requests instead of bios for request based request_queues Tejun Heo
2017-11-14 23:23 ` Shaohua Li
2017-11-15 17:18 ` [PATCH v2 " Tejun Heo
2017-11-15 17:19 ` [PATCH " Jens Axboe
2017-11-15 17:22 ` [PATCH v3 " Tejun Heo
2017-11-12 22:26 ` [PATCH 7/7] blk-throtl: don't throttle the same IO multiple times Tejun Heo
2017-11-13 4:07 ` Shaohua Li
2017-11-13 11:13 ` Tejun Heo
2017-11-13 15:57 ` Tejun Heo
2017-11-13 19:54 ` Shaohua Li
2017-11-13 19:58 ` Tejun Heo [this message]
2017-11-13 19:58 ` Shaohua Li
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=20171113195854.GJ983427@devbig577.frc2.facebook.com \
--to=tj@kernel.org \
--cc=axboe@kernel.dk \
--cc=cgroups@vger.kernel.org \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=lizefan@huawei.com \
--cc=shli@kernel.org \
/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