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Date: Wed, 03 Aug 2011 13:12:23 +0800
From: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
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To: Dave Chinner <david@fromorbit.com>
CC: Vivek Goyal <vgoyal@redhat.com>, Jens Axboe <jaxboe@fusionio.com>,
        linux-kernel@vger.kernel.org
Subject: Re: fio posixaio performance problem
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On 2011-8-3 12:47, Gui Jianfeng wrote:
> On 2011-8-3 12:06, Dave Chinner wrote:
>> On Wed, Aug 03, 2011 at 11:40:04AM +0800, Gui Jianfeng wrote:
>>> Hi,
>>>
>>> I ran a fio test to simulate qemu-kvm io behaviour.
>>> When job number is greater than 2, IO performance is
>>> really bad.
>>>
>>> 1 thread: aggrb=15,129KB/s
>>> 4 thread: aggrb=1,049KB/s
>>>
>>> Kernel: lastest upstream
>>>
>>> Any idea?
>>>
>>> ---
>>> [global]
>>> runtime=30
>>> time_based=1
>>> size=1G
>>> group_reporting=1
>>> ioengine=posixaio
>>> exec_prerun='echo 3 > /proc/sys/vm/drop_caches'
>>> thread=1
>>>
>>> [kvmio-1]
>>> description=kvmio-1
>>> numjobs=4
>>> rw=write
>>> bs=4k
>>> direct=1
>>> filename=/mnt/sda4/1G.img
>>
>> What filesystem?
> 
> Ext4

BTW, even if on Ext3, the problem is still there.

Thanks,
Gui

> 
> Thanks,
> Gui
> 
>>
>> Cheers,
>>
>> Dave.
>