From: kenneth johansson <ken@kenjo.org>
To: Grant Grundler <grundler@google.com>
Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: weird throughput on write to SATA disk
Date: Mon, 13 Oct 2008 23:22:36 +0200 [thread overview]
Message-ID: <1223932956.3947.22.camel@duo> (raw)
In-Reply-To: <da824cf30810131407m1a73bd11xa30fd118ee5a4c8f@mail.gmail.com>
On Mon, 2008-10-13 at 14:07 -0700, Grant Grundler wrote:
> On Mon, Oct 13, 2008 at 12:19 PM, kenneth johansson <ken@kenjo.org> wrote:
> > When writing data to /dev/sdb (that is the whole disk and no filesystem)
> > it starts out ok around 100MB/sec but soon end up doing considerably
> > worse. For prolonged times lasting several minutes it hovers in the
> > 20-30MB/sec.
>
> Is the application using "O_DIRECT"?
no just open then write no fancy stuff
> If not, could be issue with how VM writeback is (not) working.
the access pattern is the simplest possible. Is there any knobs I could
try to adjust.
> Can you reproduce this using fio or even "dd"?
> (See git://git.kernel.dk/fio)
dd is having the same effect.
next prev parent reply other threads:[~2008-10-13 21:22 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-13 19:19 weird throughput on write to SATA disk kenneth johansson
2008-10-13 21:07 ` Grant Grundler
2008-10-13 21:22 ` kenneth johansson [this message]
2008-10-13 21:34 ` Grant Grundler
2008-10-13 21:35 ` Grant Grundler
2008-10-13 22:19 ` kenneth johansson
2008-10-14 1:33 ` Grant Grundler
2008-10-14 9:14 ` kenneth johansson
2008-10-14 9:17 ` Tejun Heo
2008-10-14 19:10 ` kenneth johansson
2008-10-14 16:09 ` Grant Grundler
2008-10-13 22:39 ` Alan Cox
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