From: Ted Ts'o Subject: Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation Date: Fri, 19 Nov 2010 11:30:13 -0500 Message-ID: <20101119163013.GJ10039@thunk.org> References: <20101118134804.GN5618@dhcp231-156.rdu.redhat.com> <20101118141957.GK6178@parisc-linux.org> <20101118142918.GA18510@infradead.org> <1290100750.3041.72.camel@mulgrave.site> <1290168976.2570.45.camel@dolmen> <4CE68155.50705@teksavvy.com> <20101119140203.GC10039@thunk.org> <4CE69940.6040908@teksavvy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Mark Lord , Steven Whitehouse , James Bottomley , Christoph Hellwig , Matthew Wilcox , Josef Bacik , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, sandeen@redhat.com To: Lukas Czerner Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Fri, Nov 19, 2010 at 04:44:33PM +0100, Lukas Czerner wrote: > > > > But, oddly, it _is_ the default for mke2fs -t ext4, > > which really threw me for a loop recently. > > > > I though my system had locked up when suddenly everything > > went dead for a very long time (many minutes) while installing a > > new system. Yeah, the assumption was doing a single big discard (which is all mke2fs is doing) should be fast. At least on sanely implemented SSD's (i.e., like the Intel X25-M) it should be, since all that should require is a flash write to the global mapping table, declaring all of the blocks as free. If there are some incompetently implemented SSD's out there which do a flash erase of the entire SSD upon receiving a TRIM command (new flash! Part of the whole *point* of a TRIM was to increase write endurance by eliminating the need to copy blocks that really weren't in use any more by the OS when the SSD is doing a GC copy/compaction of a partially written flash sector), all I can do is do a sigh, and wish that T13 had defined a "comptently implemented SSD bit" --- not that Indilinix would admit if it they were incompetent. :-/ > That is exactly a reason why I posted a patch for > "Make blkdev_issue_discard() interruptible", but nobody seems to care. As > an addition I have patched mke2fs to inform user about ongoing discard, > also with not much attention (Ted?). Yeah, sorry. I'm still recovering from the kernel summit and plumber's. I've got to get the critical bugfix patches out to Linus before -rc3, and then I will try to get back to e2fsprogs. - Ted