From: Christoph Hellwig <hch@lst.de>
To: hugh.dickins@tiscali.co.uk
Cc: linux-mm@kvack.org
Subject: unconditional discard calls in the swap code
Date: Fri, 30 Oct 2009 07:51:02 +0100 [thread overview]
Message-ID: <20091030065102.GA2896@lst.de> (raw)
Hi Hugh,
since 6a6ba83175c029c7820765bae44692266b29e67a the swap code
unconditionally calls blkdev_issue_discard when swap clusters get freed.
So far this was harmless because only the mtd driver has discard support
wired up and it's pretty fast there (entirely done in-kernel).
We're now adding support for real UNAP/TRIM support for SCSI arrays and
SSDs, and so far all the real life ones we've dealt with have too many
performance issues to just issue the discard requests on the fly.
Because of that unconditionally enabling this code is a bad idea, it
really needs an option to disable it or even better just leave it
disabled by default for now with an option to enable it.
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next reply other threads:[~2009-10-30 6:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-30 6:51 Christoph Hellwig [this message]
2009-10-30 17:26 ` Hugh Dickins
2009-11-18 17:12 ` Christoph Hellwig
2009-11-30 17:22 ` [PATCH] mm: don't discard unused swap slots by default Christoph Hellwig
2009-11-30 18:28 ` Hugh Dickins
2009-11-30 18:58 ` Martin K. Petersen
2009-12-31 0:33 ` Hugh Dickins
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