From: Vivek Goyal <vgoyal@redhat.com>
To: Corrado Zoccolo <czoccolo@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-kernel@vger.kernel.org, axboe@kernel.dk, nauman@google.com,
dpshah@google.com, guijianfeng@cn.fujitsu.com, jmoyer@redhat.com
Subject: Re: [RFC PATCH] cfq-iosced: Implement IOPS mode and group_idle tunable V3
Date: Mon, 26 Jul 2010 10:30:23 -0400 [thread overview]
Message-ID: <20100726143023.GF12449@redhat.com> (raw)
In-Reply-To: <AANLkTi=d-2-1R_Bpk_1J7AXhTc2Kv3p8S7tE0ZsFKFDe@mail.gmail.com>
On Sat, Jul 24, 2010 at 11:07:07AM +0200, Corrado Zoccolo wrote:
> On Sat, Jul 24, 2010 at 10:51 AM, Christoph Hellwig <hch@infradead.org> wrote:
> > To me this sounds like slice_idle=0 is the right default then, as it
> > gives useful behaviour for all systems linux runs on.
> No, it will give bad performance on single disks, possibly worse than
> deadline (deadline at least sorts the requests between different
> queues, while CFQ with slice_idle=0 doesn't even do this for readers).
> Setting slice_idle to 0 should be considered only when a single
> sequential reader cannot saturate the disk bandwidth, and this happens
> only on smart enough hardware with large number of spindles.
I was thinking of writting a user space utility which can launch
increasing number of parallel direct/buffered reads from device and if
device can sustain more than 1 parallel reads with increasing throughput,
then it probably is good indicator that one might be better off with
slice_idle=0.
Will try that today...
Vivek
next prev parent reply other threads:[~2010-07-26 14:30 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-21 19:06 [RFC PATCH] cfq-iosced: Implement IOPS mode and group_idle tunable V3 Vivek Goyal
2010-07-21 19:06 ` [PATCH 1/3] cfq-iosched: Implment IOPS mode Vivek Goyal
2010-07-21 20:33 ` Jeff Moyer
2010-07-21 20:57 ` Vivek Goyal
2010-07-21 19:06 ` [PATCH 2/3] cfq-iosched: Implement a tunable group_idle Vivek Goyal
2010-07-21 19:40 ` Jeff Moyer
2010-07-21 20:13 ` Vivek Goyal
2010-07-21 20:54 ` Jeff Moyer
2010-07-21 19:06 ` [PATCH 3/3] cfq-iosched: Print number of sectors dispatched per cfqq slice Vivek Goyal
2010-07-22 5:56 ` [RFC PATCH] cfq-iosced: Implement IOPS mode and group_idle tunable V3 Christoph Hellwig
2010-07-22 14:00 ` Vivek Goyal
2010-07-24 8:51 ` Christoph Hellwig
2010-07-24 9:07 ` Corrado Zoccolo
2010-07-26 14:30 ` Vivek Goyal [this message]
2010-07-26 21:21 ` Tuning IO scheduler (Was: Re: [RFC PATCH] cfq-iosced: Implement IOPS mode and group_idle tunable V3) Vivek Goyal
2010-07-26 14:33 ` [RFC PATCH] cfq-iosced: Implement IOPS mode and group_idle tunable V3 Vivek Goyal
2010-07-29 19:57 ` Corrado Zoccolo
2010-07-26 13:51 ` Vivek Goyal
2010-07-22 20:54 ` Vivek Goyal
2010-07-22 7:08 ` Gui Jianfeng
2010-07-22 14:49 ` Vivek Goyal
2010-07-22 23:53 ` Gui Jianfeng
2010-07-26 6:58 ` Gui Jianfeng
2010-07-26 14:10 ` Vivek Goyal
2010-07-27 8:33 ` Gui Jianfeng
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=20100726143023.GF12449@redhat.com \
--to=vgoyal@redhat.com \
--cc=axboe@kernel.dk \
--cc=czoccolo@gmail.com \
--cc=dpshah@google.com \
--cc=guijianfeng@cn.fujitsu.com \
--cc=hch@infradead.org \
--cc=jmoyer@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=nauman@google.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox