From: Jens Axboe <jens.axboe@oracle.com>
To: Paolo Valente <paolo.valente@unimore.it>
Cc: Pavel Machek <pavel@ucw.cz>, linux-kernel@vger.kernel.org
Subject: Re: [RESEND][RFC] BFQ I/O Scheduler
Date: Thu, 17 Apr 2008 09:10:12 +0200 [thread overview]
Message-ID: <20080417071012.GP12774@kernel.dk> (raw)
In-Reply-To: <4806EACB.7040408@unimore.it>
On Thu, Apr 17 2008, Paolo Valente wrote:
> Pavel Machek ha scritto:
> >
> >>In the first type of tests, to achieve a higher throughput than CFQ
> >>(with the default 100 ms time slice), the maximum budget for BFQ
> >>had to be set to at least 4k sectors. Using the same value for the
> >>
> >
> >Hmm, 4k sectors is ~40 seconds worst case, no? That's quite long...
> >
> Actually, in the worst case among our tests, the aggregate throughput
> with 4k sectors was ~ 20 MB/s, hence the time for 4k sectors ~ 4k * 512
> / 20M = 100 ms.
That's not worse case, it is pretty close to BEST case. Worst case is 4k
of sectors, with each being a 512b IO and causing a full stroke seek.
For that type of workload, even a modern sata hard drive will be doing
500kb/sec or less. That's rougly a thousand sectors per seconds, so ~4
seconds worst case for 4k sectors.
--
Jens Axboe
next prev parent reply other threads:[~2008-04-17 7:10 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-01 15:29 [RESEND][RFC] BFQ I/O Scheduler Fabio Checconi
2008-04-15 8:22 ` Jens Axboe
2008-04-15 9:11 ` Fabio Checconi
2008-04-15 12:42 ` Jens Axboe
2008-04-15 18:08 ` Fabio Checconi
2008-04-16 6:48 ` Paolo Valente
2008-04-18 1:26 ` Aaron Carroll
2008-04-16 18:44 ` Pavel Machek
2008-04-17 6:14 ` Paolo Valente
2008-04-17 7:10 ` Jens Axboe [this message]
2008-04-17 8:26 ` Paolo Valente
2008-04-17 8:30 ` Jens Axboe
2008-04-17 9:24 ` Paolo Valente
2008-04-17 9:27 ` Jens Axboe
2008-04-17 10:19 ` Aaron Carroll
2008-04-17 10:21 ` Jens Axboe
2008-04-17 11:30 ` Fabio Checconi
2008-04-17 15:19 ` Avi Kivity
2008-04-17 15:47 ` Paolo Valente
2008-04-17 15:51 ` Avi Kivity
2008-04-17 18:12 ` Paolo Valente
2008-04-17 23:44 ` Aaron Carroll
2008-04-17 10:24 ` Aaron Carroll
2008-04-17 11:14 ` Fabio Checconi
2008-04-17 12:14 ` Aaron Carroll
2008-04-17 13:54 ` Jens Axboe
2008-04-17 15:18 ` Paolo Valente
2008-04-17 8:48 ` Pavel Machek
2008-04-17 8:57 ` Jens Axboe
2008-04-17 9:14 ` Fabio Checconi
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=20080417071012.GP12774@kernel.dk \
--to=jens.axboe@oracle.com \
--cc=linux-kernel@vger.kernel.org \
--cc=paolo.valente@unimore.it \
--cc=pavel@ucw.cz \
/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.