linux-kernel - Re: fio posixaio performance problem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <4E3A5FDD.2010004@fusionio.com>
Date:	Thu, 4 Aug 2011 11:01:17 +0200
From:	Jens Axboe <jaxboe@...ionio.com>
To:	Gui Jianfeng <guijianfeng@...fujitsu.com>
CC:	Shaohua Li <shli@...nel.org>, Vivek Goyal <vgoyal@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: fio posixaio performance problem

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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/