From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Tejun Heo <tj@kernel.org>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
James Bottomley <James.Bottomley@HansenPartnership.com>,
linux-ide@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] libata: Whitelist SSDs that are known to properly return zeroes after TRIM
Date: Tue, 06 Jan 2015 19:05:40 -0500 [thread overview]
Message-ID: <yq1387n8nfv.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <20150105162830.GP15833@htj.dyndns.org> (Tejun Heo's message of "Mon, 5 Jan 2015 11:28:30 -0500")
>>>>> "Tejun" == Tejun Heo <tj@kernel.org> writes:
>> The other use case is the filesystem one where it is common to zero
>> block ranges for bitmaps, etc. In many workloads there's is a
>> significant win to trimming over writing out many blocks of zeroes.
Tejun> Isn't that kinda niche and specialized tho?
I don't think so. There are two reasons for zeroing block ranges:
1) To ensure they contain zeroes on subsequent reads
2) To preallocate them or anchor them down on thin provisioned devices
The filesystem folks have specifically asked to be able to make that
distinction. Hence the patch that changes blkdev_issue_zeroout().
You really don't want to write out gobs and gobs of zeroes and cause
unnecessary flash wear if all you care about is the blocks being in a
deterministic state.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2015-01-07 0:05 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-04 2:44 [PATCH] libata: Whitelist SSDs that are known to properly return zeroes after TRIM Martin K. Petersen
2014-12-04 3:02 ` Phillip Susi
2014-12-04 3:24 ` Martin K. Petersen
2014-12-04 3:28 ` Phillip Susi
2014-12-04 3:35 ` Martin K. Petersen
2014-12-04 4:40 ` Phillip Susi
2014-12-05 1:53 ` Martin K. Petersen
2014-12-04 21:49 ` One Thousand Gnomes
2014-12-05 2:46 ` Martin K. Petersen
2014-12-04 17:06 ` Tejun Heo
2014-12-05 2:13 ` Martin K. Petersen
2014-12-05 14:51 ` Tejun Heo
2014-12-10 4:09 ` James Bottomley
2014-12-10 14:29 ` Tejun Heo
2014-12-10 20:34 ` James Bottomley
2014-12-10 21:02 ` Martin K. Petersen
2014-12-12 8:35 ` Ming Lei
2015-01-05 16:28 ` Tejun Heo
2015-01-07 0:05 ` Martin K. Petersen [this message]
2015-01-07 2:54 ` Tejun Heo
2015-01-07 4:15 ` Dave Chinner
2015-01-07 15:26 ` Tejun Heo
2015-01-08 14:28 ` Martin K. Petersen
2015-01-08 15:11 ` Tejun Heo
2015-01-08 15:34 ` Martin K. Petersen
2015-01-08 15:36 ` Tejun Heo
2015-01-08 15:58 ` Tim Small
2015-01-09 20:52 ` Martin K. Petersen
2015-01-09 21:39 ` Tejun Heo
2015-01-08 14:29 ` Martin K. Petersen
2015-01-08 4:05 ` Phillip Susi
2015-01-08 4:58 ` Andreas Dilger
2015-01-08 14:09 ` Phillip Susi
2015-01-08 22:31 ` Andreas Dilger
2014-12-10 15:43 ` Tim Small
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