From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 653A96B004D for ; Sun, 16 Aug 2009 22:05:42 -0400 (EDT) Message-ID: <4A88BAF5.2000009@rtr.ca> Date: Sun, 16 Aug 2009 22:05:41 -0400 From: Mark Lord MIME-Version: 1.0 Subject: Re: Discard support (was Re: [PATCH] swap: send callback when swap slot is freed) References: <200908122007.43522.ngupta@vflare.org> <20090813151312.GA13559@linux.intel.com> <20090813162621.GB1915@phenom2.trippelsdorf.de> <87f94c370908131115r680a7523w3cdbc78b9e82373c@mail.gmail.com> <3e8340490908131354q167840fcv124ec56c92bbb830@mail.gmail.com> <4A85E0DC.9040101@rtr.ca> <20090814234539.GE27148@parisc-linux.org> <1250341176.4159.2.camel@mulgrave.site> <4A86B69C.7090001@rtr.ca> <1250344518.4159.4.camel@mulgrave.site> <20090816150530.2bae6d1f@lxorguk.ukuu.org.uk> <20090816083434.2ce69859@infradead.org> <20090816202905.59efa611@lxorguk.ukuu.org.uk> <4A8890B8.6070409@anonymous.org.uk> In-Reply-To: <4A8890B8.6070409@anonymous.org.uk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: John Robinson Cc: Alan Cox , Arjan van de Ven , James Bottomley , Chris Worley , Matthew Wilcox , Bryan Donlan , david@lang.hm, Greg Freemyer , Markus Trippelsdorf , Matthew Wilcox , Hugh Dickins , Nitin Gupta , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, Linux RAID List-ID: John Robinson wrote: .. > I'm slightly out of my depth here, but: if a single TRIM is issued, > which apparently returns quickly, can one then revert to issuing > ordinary commands like reads and writes and have them complete as > quickly as they normally do, or does any following command have to wait > until the trim completes? This could be useful if it turned out we won't > stall these devices as long as we don't issue more than one TRIM every > few seconds; we could keep a TRIM coalesce queue down to being (say) 5 > seconds long (or at least, a configurable small number of seconds). .. I have not attempted to instrument that, but I suspect that any command after the TRIM has to wait. Don't know for sure until somebody measures it though. One thing I do know, is that Matthew's first cut of TRIM support means it takes half an hour to do "rm -r" on a kernel source tree. -ml -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org