From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Tejun Heo <htejun@gmail.com>
Cc: "zhao, forrest" <forrest.zhao@intel.com>,
linux-ide@vger.kernel.org, Jens Axboe <axboe@suse.de>
Subject: Re: A question about NCQ
Date: Wed, 17 May 2006 14:04:27 +1000 [thread overview]
Message-ID: <446AA0CB.60208@yahoo.com.au> (raw)
In-Reply-To: <446A9E65.9040608@gmail.com>
Tejun Heo wrote:
>
>Anyways, anticipatory rules, great. I don't know why NCQ is showing
>worse performance w/ AS, but I'm pretty sure it's something which can be
>fixed. Jens, Nick, any ideas?
>
Thanks for the numbers, interesting.
Anticipatory basically tries pretty hard to control disk command
queues because they can result in starvation... not exactly sure
why it is _worse_ with NCQ than without, maybe the drive isn't too
smart or there is a bad interaction with AS.
I don't see any trivial bugs in AS that would cause this, but there
may be one...
It's unfortunate that we don't have a grand unified IO scheduler
that does everything well (except perhaps noop functionality). It
is something I guess Jens and I (or maybe someone completely
different) should get together with and try to make progress on one
day.
--
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-05-17 4:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-16 10:01 A question about NCQ zhao, forrest
2006-05-16 10:49 ` Tejun Heo
2006-05-17 2:21 ` zhao, forrest
2006-05-17 2:37 ` Tejun Heo
2006-05-17 3:24 ` zhao, forrest
2006-05-17 3:54 ` Tejun Heo
2006-05-17 4:04 ` Nick Piggin [this message]
2006-05-17 3:19 ` Jeff Garzik
2006-05-17 3:50 ` zhao, forrest
2006-05-17 14:31 ` Mark Lord
2006-05-18 1:56 ` Tejun Heo
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