From: Jens Axboe <jaxboe@fusionio.com>
To: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Cc: Shaohua Li <shli@kernel.org>, Vivek Goyal <vgoyal@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: fio posixaio performance problem
Date: Thu, 4 Aug 2011 11:01:17 +0200 [thread overview]
Message-ID: <4E3A5FDD.2010004@fusionio.com> (raw)
In-Reply-To: <4E3A59DD.6010907@cn.fujitsu.com>
On 2011-08-04 10:35, Gui Jianfeng wrote:
>> looks the system does a write in every 8ms. This is quite wrong. does
>> the posixaio
>> engine have something wrong? can you use a new fio or try libaio please.
>
> Yes, I also highly suspect that fio's posixaio engine works bad.
> On the other hand, I'm not sure why preempting in cfqs doesn't happen.
> It seems requests from different threads is close enough...
Can't be ruled out that there's a bug in the posixaio engine. It's
perhaps 100 lines of interesting code in there, so should be easy enough
to audit. Unless it's an interaction with the fio core of course.
Since you're using a queue depth of 1, every getevents call would end up
in aio_suspend() waiting for the previously submitted one. That should
interleave just fine with the other threads, though.
--
Jens Axboe
next prev parent reply other threads:[~2011-08-04 9:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-03 3:40 fio posixaio performance problem Gui Jianfeng
2011-08-03 4:06 ` Dave Chinner
2011-08-03 4:47 ` Gui Jianfeng
2011-08-03 5:12 ` Gui Jianfeng
2011-08-03 7:38 ` Shaohua Li
2011-08-03 8:11 ` Gui Jianfeng
2011-08-03 8:22 ` Shaohua Li
2011-08-03 9:48 ` Gui Jianfeng
2011-08-03 15:45 ` Vivek Goyal
2011-08-03 17:51 ` Vivek Goyal
2011-08-04 0:53 ` Shaohua Li
2011-08-04 2:00 ` Gui Jianfeng
2011-08-04 3:14 ` Shaohua Li
[not found] ` <4E3A4DF7.3020605@cn.fujitsu.com>
2011-08-04 8:25 ` Shaohua Li
2011-08-04 8:35 ` Gui Jianfeng
2011-08-04 9:01 ` Jens Axboe [this message]
2011-08-04 14:12 ` Vivek Goyal
2011-08-05 0:56 ` Gui Jianfeng
2011-08-05 1:31 ` Gui Jianfeng
2011-08-04 1:55 ` Gui Jianfeng
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