From: Jens Axboe <jens.axboe@oracle.com>
To: Divyesh Shah <dpshah@google.com>
Cc: vgoyal@redhat.com, linux-kernel@vger.kernel.org,
nauman@google.com, ctalbott@google.com
Subject: Re: [PATCH] cfq-iosched: Fix the incorrect timeslice accounting with forced_dispatch.
Date: Fri, 9 Apr 2010 09:29:16 +0200 [thread overview]
Message-ID: <20100409072915.GF10103@kernel.dk> (raw)
In-Reply-To: <20100409021054.13511.52377.stgit@austin.mtv.corp.google.com>
On Thu, Apr 08 2010, Divyesh Shah wrote:
> When CFQ dispatches requests forcefully due to a barrier or changing iosched,
> it runs through all cfqq's dispatching requests and then expires each queue.
> However, it does not activate a cfqq before flushing its IOs resulting in
> using stale values for computing slice_used.
> This patch fixes it by calling activate queue before flushing reuqests from
> each queue.
>
> This is useful mostly for barrier requests because when the iosched is changing
> it really doesnt matter if we have incorrect accounting since we're going to
> break down all structures anyway.
>
> We also now expire the current timeslice before moving on with the dispatch
> to accurately account slice used for that cfqq.
Good catch, applied for 2.6.34.
--
Jens Axboe
next prev parent reply other threads:[~2010-04-09 7:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-09 2:19 [PATCH] cfq-iosched: Fix the incorrect timeslice accounting with forced_dispatch Divyesh Shah
2010-04-09 7:29 ` Jens Axboe [this message]
2010-04-09 14:09 ` Vivek Goyal
2010-04-09 15:25 ` Divyesh Shah
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=20100409072915.GF10103@kernel.dk \
--to=jens.axboe@oracle.com \
--cc=ctalbott@google.com \
--cc=dpshah@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=nauman@google.com \
--cc=vgoyal@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.