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From: Michael Tokarev <mjt@tls.msk.ru>
To: Jeremy Higdon <jeremy@sgi.com>
Cc: David Chinner <dgc@sgi.com>, Ric Wheeler <ric@emc.com>,
	device-mapper development <dm-devel@redhat.com>,
	Andi Kleen <andi@firstfloor.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [dm-devel] Re: [PATCH] Implement barrier support for single device DM devices
Date: Tue, 19 Feb 2008 10:58:31 +0300	[thread overview]
Message-ID: <47BA8C27.6020108@msgid.tls.msk.ru> (raw)
In-Reply-To: <20080219071948.GA244758@sgi.com>

Jeremy Higdon wrote:
[]
> I'll put it even more strongly.  My experience is that disabling write
> cache plus disabling barriers is often much faster than enabling both
> barriers and write cache enabled, when doing metadata intensive
> operations, as long as you have a drive that is good at CTQ/NCQ.

Now, and it's VERY interesting at least for me (and is off-topic in
this thread) -- which drive(s) are good at NCQ?  I tried numerous SATA
(NCQ is about sata, right? :) drives, but NCQ either does nothing in
terms of performance or hurts.  Yesterday we ordered another drive
from Hitachi (their "raid edition" thing), -- will try it tomorrow,
but I've no hope here as it's some 5th or 6th model/brand already.

(Ol'good SCSI drives, even 10 years old, shows large difference when
TCQ is enabled...)

Thanks!

  reply	other threads:[~2008-02-19  7:59 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-15 12:08 [PATCH] Implement barrier support for single device DM devices Andi Kleen
2008-02-15 12:20 ` Alasdair G Kergon
2008-02-15 13:07   ` Michael Tokarev
2008-02-15 14:20     ` Andi Kleen
2008-02-15 14:12       ` [dm-devel] " Alasdair G Kergon
2008-02-15 15:34         ` Andi Kleen
2008-02-15 15:31           ` Alan Cox
2008-02-18 12:48         ` Ric Wheeler
2008-02-18 13:24           ` Michael Tokarev
2008-02-18 13:52             ` Ric Wheeler
2008-02-19  2:45               ` Alasdair G Kergon
2008-05-16 19:55                 ` Mike Snitzer
2008-05-16 21:48                   ` Andi Kleen
2008-02-18 22:16             ` David Chinner
2008-02-19  2:56               ` Alasdair G Kergon
2008-02-19  5:36                 ` David Chinner
2008-02-19  9:43                 ` Andi Kleen
2008-02-19  7:19               ` Jeremy Higdon
2008-02-19  7:58                 ` Michael Tokarev [this message]
2008-02-20 13:38                 ` Ric Wheeler
2008-02-21  3:29                 ` Neil Brown
2008-02-21  3:39               ` Neil Brown
2008-02-17 23:31     ` David Chinner
2008-02-19  2:39     ` Alasdair G Kergon
2008-02-19 11:12       ` David Chinner

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