From: "Grant Grundler" <grundler@google.com>
To: kenneth johansson <ken@kenjo.org>
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 14:07:15 -0700 [thread overview]
Message-ID: <da824cf30810131407m1a73bd11xa30fd118ee5a4c8f@mail.gmail.com> (raw)
In-Reply-To: <1223925629.3947.7.camel@duo>
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"?
If not, could be issue with how VM writeback is (not) working.
Can you reproduce this using fio or even "dd"?
(See git://git.kernel.dk/fio)
grant
>
> This happens on two different SATA disk one samsung and one seagate and
> on both 2.6.26 and 2.6.27 kernel. The disk are connected to the external
> esata connector. Controller is 00:1f.2 SATA controller: Intel
> Corporation 82801HB (ICH8) 4 port SATA AHCI Controller (rev 02)
>
> What could be the reason for this ?? reading is no problem.
>
>
>
next prev parent reply other threads:[~2008-10-13 21:07 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 [this message]
2008-10-13 21:22 ` kenneth johansson
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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