linux-ext4 - Re: Is TRIM/DISCARD going to be a performance problem?

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Message-ID: <82k540dvve.fsf@mid.bfk.de>
Date:	Fri, 29 May 2009 12:52:21 +0200
From:	Florian Weimer <fweimer@....de>
To:	Matthew Wilcox <willy@...ux.intel.com>
Cc:	Chris Mason <chris.mason@...cle.com>, Theodore Tso <tytso@....edu>,
	Jens Axboe <jens.axboe@...cle.com>,
	Ric Wheeler <rwheeler@...hat.com>,
	linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: Is TRIM/DISCARD going to be a performance problem?

* Matthew Wilcox:

> Actually, that's the exact opposite of what you want.  You want to try
> to reuse blocks that are scheduled for trimming so that we never have to
> send the command at all.

I thought that the device would receive as many TRIM commands as
possible, to aid its internal reorganization process?  A write which
overwrites a whole block could be equivalent, but it may not be a good
idea to artificially increase I/O traffic to turn partial writes to
unused blocks into full-block writes.

-- 
Florian Weimer                <fweimer@....de>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstraße 100              tel: +49-721-96201-1
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