linux-kernel - Re: Higher than expected disk write(2) latency

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

Message-ID: <48760BFB.90007@fastmq.com>
Date:	Thu, 10 Jul 2008 15:17:47 +0200
From:	Martin Sustrik <sustrik@...tmq.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Martin Lucina <mato@...elna.sk>, linux-kernel@...r.kernel.org
Subject: Re: Higher than expected disk write(2) latency

Hi Alan,

>> What we see is that AIO performs rather bad while we are still 
>> enqueueing more writes (it misses right position on the disk and has to 
>> do superfluous disk revolvings), however, once we stop enqueueing new 
>> write request, those already in the queue are processed swiftly.
> 
> Which disk scheduler are you using - some of the disk schedulers
> intentionally delay writes to try and get better block merging.

It's CFQ. Does it delay writes? And if so, what should we use instead?

Thanks.
Martin
--
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/