From: Oleg Nesterov <oleg@redhat.com>
To: Jens Axboe <axboe@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Jens Axboe <axboe@kernel.dk>, Josef Bacik <josef@toxicpanda.com>,
Kernel Team <Kernel-team@fb.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH 1/2] wait: add wq_has_multiple_sleepers helper
Date: Thu, 11 Jul 2019 13:45:43 +0200 [thread overview]
Message-ID: <20190711114543.GA14901@redhat.com> (raw)
In-Reply-To: <752dbdc9-945d-e70c-e6f3-0c48932c7f60@fb.com>
Jens,
I managed to convince myself I understand why 2/2 needs this change...
But rq_qos_wait() still looks suspicious to me. Why can't the main loop
"break" right after io_schedule()? rq_qos_wake_function() either sets
data->got_token = true or it doesn't wakeup the waiter sleeping in
io_schedule()
This means that data.got_token = F at the 2nd iteration is only possible
after a spurious wakeup, right? But in this case we need to set state =
TASK_UNINTERRUPTIBLE again to avoid busy-wait looping ?
Oleg.
next prev parent reply other threads:[~2019-07-11 11:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-10 19:52 [PATCH 1/2] wait: add wq_has_multiple_sleepers helper Josef Bacik
2019-07-10 19:52 ` [PATCH 2/2] rq-qos: fix missed wake-ups in rq_qos_throttle Josef Bacik
2019-07-10 20:23 ` [PATCH 1/2] wait: add wq_has_multiple_sleepers helper Jens Axboe
2019-07-10 20:35 ` Peter Zijlstra
2019-07-10 20:39 ` Jens Axboe
2019-07-11 11:45 ` Oleg Nesterov [this message]
2019-07-11 13:40 ` Oleg Nesterov
2019-07-11 19:21 ` Josef Bacik
2019-07-12 8:05 ` Oleg Nesterov
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=20190711114543.GA14901@redhat.com \
--to=oleg@redhat.com \
--cc=Kernel-team@fb.com \
--cc=axboe@fb.com \
--cc=axboe@kernel.dk \
--cc=josef@toxicpanda.com \
--cc=linux-block@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.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;
as well as URLs for NNTP newsgroup(s).