From: Shaohua Li <shaohua.li@intel.com>
To: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>, Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
linux-next@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH block:for-3.3/core] block: disable ELEVATOR_INSERT_SORT_MERGE
Date: Fri, 06 Jan 2012 16:15:57 +0800 [thread overview]
Message-ID: <1325837757.22361.538.camel@sli10-conroe> (raw)
In-Reply-To: <CAOS58YPUgK4J6j1Gme9O9HeL7GrwnJU8QTVKbVLA9cEXPQ1kag@mail.gmail.com>
On Thu, 2012-01-05 at 20:38 -0800, Tejun Heo wrote:
> Hello,
>
> On Thu, Jan 5, 2012 at 8:19 PM, Shaohua Li <shaohua.li@intel.com> wrote:
> >> For detailed discussion of the bug:
> >>
> >> http://thread.gmane.org/gmane.linux.kernel.next/20064/focus=20159
> >>
> > this is overkill. when plug is added, we found huge performance
> > regression, that's why we add INSERT_SORT_MERGE.
>
> With what workload? I suspect most of the improvements is from merging
> across different cfqqs, no? The whole recursive thing can't be very
> useful if cross-cfqq merging isn't allowed. Maybe there are specific
> cases where last_merge hint merging can be specially effective. I
> don't know. Regardless, this is an apparent bug and the block tree
> will be pushed mainline pretty soon. If necessary, fix it better
> later. Doing complex things inside merge window usually isn't a good
> idea.
it's not related to the recursive merge. I forgot the detail of the
workload why we add INSERT_SORT_MERGE, it's added several months ago
anyway.
Obviously we shouldn't do complex things inside the merge window. I just
didn't agree to disable INSERT_SORT_MERGE, which will bring performance
regression for sure. Can we just change CFQ like your first path?
Thanks,
Shaohua
next prev parent reply other threads:[~2012-01-06 8:01 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20111221174733.9ba0861e762e8d96844b060b@canb.auug.org.au>
2011-12-21 23:15 ` linux-next: Tree for Dec 21 Andrew Morton
2011-12-22 23:08 ` Andrew Morton
2011-12-22 23:20 ` Tejun Heo
2011-12-22 23:24 ` Andrew Morton
2011-12-22 23:38 ` Tejun Heo
2011-12-22 23:44 ` Andrew Morton
2011-12-22 23:46 ` Tejun Heo
2011-12-23 0:42 ` Tejun Heo
2011-12-24 5:13 ` Hugh Dickins
2011-12-25 1:02 ` [PATCH block/for-3.3/core] block: an exiting task should be allowed to create io_context Tejun Heo
2011-12-25 13:29 ` Jens Axboe
2011-12-27 22:07 ` Andrew Morton
2011-12-28 8:33 ` Hugh Dickins
2011-12-28 16:48 ` Tejun Heo
2011-12-28 17:50 ` Hugh Dickins
2011-12-28 17:55 ` Tejun Heo
2011-12-28 21:19 ` Tejun Heo
2012-01-03 17:35 ` Tejun Heo
2012-01-03 17:59 ` Tejun Heo
2012-01-03 20:09 ` Tejun Heo
2012-01-03 20:20 ` Jens Axboe
2012-01-03 22:13 ` Tejun Heo
2012-01-03 22:35 ` Tejun Heo
2012-01-05 1:24 ` Tejun Heo
2012-01-05 18:36 ` Hugh Dickins
2012-01-05 18:38 ` Tejun Heo
2012-01-06 2:17 ` [PATCH block:for-3.3/core] cfq: merged request shouldn't jump to a different cfqq Tejun Heo
2012-01-06 2:36 ` Tejun Heo
2012-01-06 3:14 ` Shaohua Li
2012-01-06 3:04 ` Tejun Heo
2012-01-06 3:30 ` Tejun Heo
2012-01-06 3:52 ` [PATCH block:for-3.3/core] block: disable ELEVATOR_INSERT_SORT_MERGE Tejun Heo
2012-01-06 4:19 ` Shaohua Li
2012-01-06 4:38 ` Tejun Heo
2012-01-06 8:15 ` Shaohua Li [this message]
2012-01-06 15:34 ` Tejun Heo
2012-01-06 3:34 ` [PATCH block:for-3.3/core] cfq: merged request shouldn't jump to a different cfqq Shaohua Li
2012-01-06 3:22 ` Tejun Heo
2012-01-06 4:15 ` Shaohua Li
2012-01-06 4:40 ` Tejun Heo
2012-01-06 2:47 ` 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=1325837757.22361.538.camel@sli10-conroe \
--to=shaohua.li@intel.com \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=hughd@google.com \
--cc=linux-ide@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-next@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=sfr@canb.auug.org.au \
--cc=tj@kernel.org \
--cc=x86@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;
as well as URLs for NNTP newsgroup(s).