From: Arjan van de Ven <arjan@linux.intel.com>
To: Al Boldi <a1426z@gawab.com>
Cc: Arjan van de Ven <arjan@infradead.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: CFQ will be the new default IO scheduler - why?
Date: Tue, 25 Jul 2006 06:59:21 +0200 [thread overview]
Message-ID: <44C5A529.9060306@linux.intel.com> (raw)
In-Reply-To: <200607250756.49071.a1426z@gawab.com>
Al Boldi wrote:
> Arjan van de Ven wrote:
>>>> Should there be a default scheduler per filesystem? As some
>>>> filesystems may perform better/worse with one over another?
>>> It's currently perDevice, and should probably be extended to perMount.
>> Hi,
>
> Hi!
>
>> per mount is going to be "not funny". I assume the situation you are
>> aiming for is the "3 partitions on a disk, each wants its own elevator".
>> The way the kernel currently works is that IO requests the filesystem
>> does are first flattened into an IO for the entire device (eg the
>> partition mapping is done) and THEN the IO scheduler gets involved to
>> schedule the IO on a per disk basis.
>
> IC. That probably explains why concurrent io-procs have such a hard time
> getting through to the disk. They probably just hang in the flatting phase,
> waiting for something to take care of their requests.
>
flattening is just an addition in the cpu, that's just really boring and shouldn't be visible anywhere
performance wise
next prev parent reply other threads:[~2006-07-25 4:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-24 15:57 CFQ will be the new default IO scheduler - why? Al Boldi
2006-07-24 16:33 ` Arjan van de Ven
2006-07-25 4:56 ` Al Boldi
2006-07-25 4:59 ` Arjan van de Ven [this message]
2006-07-25 18:27 ` Al Boldi
-- strict thread matches above, loose matches on Subject: below --
2006-07-23 19:08 Paa Paa
2006-07-24 8:29 ` Matthias Andree
2006-07-24 12:41 ` Justin Piszcz
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