linux-kernel - Re: [PATCH 2/2] block: create ioctl to discard-or-zeroout a range of blocks

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Message-ID: <x491t7795ro.fsf@segfault.boston.devel.redhat.com>
Date:	Fri, 18 Mar 2016 11:15:23 -0400
From:	Jeff Moyer <jmoyer@...hat.com>
To:	"Theodore Ts'o" <tytso@....edu>
Cc:	Chris Mason <clm@...com>, Andreas Dilger <adilger@...ger.ca>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Gregory Farnum <greg@...gs42.com>,
	Eric Sandeen <sandeen@...hat.com>,
	"Darrick J. Wong" <darrick.wong@...cle.com>,
	Dave Chinner <david@...morbit.com>,
	Ric Wheeler <rwheeler@...hat.com>,
	Andy Lutomirski <luto@...capital.net>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Martin Petersen <martin.petersen@...cle.com>,
	Christoph Hellwig <hch@...radead.org>,
	Jens Axboe <axboe@...nel.dk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux API <linux-api@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	shane.seymour@....com, Bruce Fields <bfields@...ldses.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Jeff Layton <jlayton@...chiereds.net>
Subject: Re: [PATCH 2/2] block: create ioctl to discard-or-zeroout a range of blocks

"Theodore Ts'o" <tytso@....edu> writes:

> I do think that using TRIM in various causes where we are doing an
> fallocate does make sense for non-rotational devices.  In general TRIM
> should be fast enough that that I'd be surprised that people would be
> complaining --- especially since most of the time, fallocate isn't on
> the timing-critical path of most applications.

TRIM/UNMAP isn't just supported on solid state devices, though.  I do
recall some enterprise thinly provisioned storage that would take ages
to discard large regions.  I think that caused us to change the defaults
for mkfs, right?

Cheers,
Jeff