linux-kernel - Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4CE59C9E.6050902@teksavvy.com>
Date:	Thu, 18 Nov 2010 16:37:34 -0500
From:	Mark Lord <kernel@...savvy.com>
To:	James Bottomley <James.Bottomley@...e.de>
CC:	Christoph Hellwig <hch@...radead.org>,
	Matthew Wilcox <matthew@....cx>,
	Josef Bacik <josef@...hat.com>,
	Lukas Czerner <lczerner@...hat.com>, tytso@....edu,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, sandeen@...hat.com
Subject: Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation

On 10-11-18 12:19 PM, James Bottomley wrote:
>
> Not stepping into the debate: I'm happy to see punch go to the mapping
> data and FITRIM pick it up later.
>
> However, I think it's time to question whether we actually still want to
> allow online discard at all.  Most of the benchmarks show it to be a net
> lose to almost everything (either SSD or Thinly Provisioned arrays), so
> it's become an "enable this to degrade performance" option with no
> upside.

I also suspect that online TRIM exerts significant premature wear on the SSDs.
TRIM operations most likely trigger immediate copy/erase operations internal
to most SSDs, often regardless of the amount of data being trimmed.

Performing a 256KB erase because of a 1024-byte TRIM, over and over, is going
to harm the expected lifetime of an SSD.  Sure, some SSDs may do things differently
internally, but I don't see it working that way in much of the current crop of SSDs.

Currently, I patch my kernels to remove the automatic online TRIMs.
Is there a knob somewhere for this in the later kernels?

Cheers
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/