From: Jan Kara <jack@suse.cz>
To: linux-block@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>
Subject: WBT for SQ devices interface
Date: Tue, 11 Apr 2017 11:38:27 +0200 [thread overview]
Message-ID: <20170411093827.GC2471@quack2.suse.cz> (raw)
Hi,
when testing my fix for 0-day reports with writeback throttling I came
across somewhat unexpected behavior with user interface of writeback
throttling. So currently if CFQ is used as an IO scheduler, we disable
writeback throttling because they don't go well together. However when user
has CONFIG_BLK_WBT_SQ=y and switches IO scheduler to NOOP or DEADLINE
writeback throttling still stays disabled. This is somewhat unexpected
especially because the switching of IO scheduler from CFQ to something else
can have happened behind user's back by some udev rule or so. So basically
CONFIG_DEFAULT_CFQ=y and CONFIG_BLK_WBT_SQ=y don't make sense together.
So do people thing we should enable WBT if CONFIG_BLK_WBT_SQ=y and IO
scheduler is switched from CFQ to something else?
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next reply other threads:[~2017-04-11 9:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-11 9:38 Jan Kara [this message]
2017-04-11 15:16 ` WBT for SQ devices interface Holger Hoffstätte
2017-04-11 16:22 ` 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=20170411093827.GC2471@quack2.suse.cz \
--to=jack@suse.cz \
--cc=axboe@kernel.dk \
--cc=linux-block@vger.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