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 10:33:00 -0400 [thread overview]
Message-ID: <20100726143300.GG12449@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).
Not sure if CFQ will be worse than deadline with slice_idle=0. CFQ has
some inbuilt things which should help.
- Readers preempt Writers
- All writers go in one single queue (at one prio level), readers get
their individual queues and can outnumber writers.
So I guess CFQ with slice_idle=0 should not be worse than deadline in terms
of read latencies.
Vivek
next prev parent reply other threads:[~2010-07-26 14:33 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
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 ` Vivek Goyal [this message]
2010-07-29 19:57 ` [RFC PATCH] cfq-iosced: Implement IOPS mode and group_idle tunable V3 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
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