From: Vivek Goyal <vgoyal@redhat.com>
To: Shaohua Li <shaohua.li@intel.com>
Cc: Dave Chinner <david@fromorbit.com>,
linux-kernel@vger.kernel.org, axboe@kernel.dk, jmoyer@redhat.com,
zhu.yanhai@gmail.com
Subject: Re: [RFC 0/3]block: An IOPS based ioscheduler
Date: Wed, 18 Jan 2012 08:04:25 -0500 [thread overview]
Message-ID: <20120118130425.GA30204@redhat.com> (raw)
In-Reply-To: <1326849637.22361.616.camel@sli10-conroe>
On Wed, Jan 18, 2012 at 09:20:37AM +0800, Shaohua Li wrote:
[..]
> > I think trying to make to make CFQ work (Or trying to come up with CFQ
> > like IOPS scheduler) on these fast devices might not lead us anywhere.
> If only performance matters, I'd rather use noop for ssd. There is
> requirement to have cgroup support (maybe ioprio) to give different
> tasks different bandwidth.
Sure but the issue is that we need to idle in an effort to prioritize
a task and idling kills performance. So you can implement something but
I have doubts that on a fast hardware it is going to be very useful.
Another issue is that with flash based storage, it can drive really deep
queue depths. If that's the case, then just ioscheduler can't solve the
prioritazaion issues (until and unless ioscheduler does not drive deep
queue depths and kills performance). We need some kind of cooperation
from device (like device understanding the notion of iopriority), so
that device can prioritize the requests and one need not to idle. That
way, we might be able to get service differentiation while getting
reasonable throughput.
Thanks
Vivek
next prev parent reply other threads:[~2012-01-18 13:04 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-04 6:53 [RFC 0/3]block: An IOPS based ioscheduler Shaohua Li
2012-01-04 6:53 ` [RFC 1/3]block: seperate CFQ io context management code Shaohua Li
2012-01-04 8:19 ` Namhyung Kim
2012-01-04 6:53 ` [RFC 2/3]block: FIOPS ioscheduler core Shaohua Li
2012-01-06 6:05 ` Namjae Jeon
2012-01-07 1:06 ` Zhu Yanhai
2012-01-04 6:53 ` [RFC 3/3]block: fiops read/write request scale Shaohua Li
2012-01-04 7:19 ` [RFC 0/3]block: An IOPS based ioscheduler Dave Chinner
2012-01-05 6:50 ` Shaohua Li
2012-01-06 5:12 ` Shaohua Li
2012-01-06 9:10 ` Namhyung Kim
2012-01-06 14:37 ` Jan Kara
2012-01-09 1:26 ` Shaohua Li
2012-01-15 22:32 ` Vivek Goyal
2012-01-08 22:16 ` Dave Chinner
2012-01-09 1:09 ` Shaohua Li
2012-01-15 22:45 ` Vivek Goyal
2012-01-16 4:36 ` Shaohua Li
2012-01-16 7:11 ` Vivek Goyal
2012-01-16 7:55 ` Shaohua Li
2012-01-16 8:29 ` Vivek Goyal
2012-01-17 1:06 ` Shaohua Li
2012-01-17 9:02 ` Vivek Goyal
2012-01-18 1:20 ` Shaohua Li
2012-01-18 13:04 ` Vivek Goyal [this message]
2012-01-19 1:21 ` Shaohua Li
2012-01-15 22:28 ` Vivek Goyal
2012-01-06 9:41 ` Zhu Yanhai
2012-01-15 22:24 ` Vivek Goyal
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