From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 1AE0C6B004F for ; Fri, 14 Aug 2009 19:45:39 -0400 (EDT) Date: Fri, 14 Aug 2009 17:45:39 -0600 From: Matthew Wilcox Subject: Re: Discard support (was Re: [PATCH] swap: send callback when swap slot is freed) Message-ID: <20090814234539.GE27148@parisc-linux.org> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Chris Worley Cc: Mark Lord , 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: On Fri, Aug 14, 2009 at 05:21:32PM -0600, Chris Worley wrote: > Sooner is better than waiting to coalesce. The longer an LBA is > inactive, the better for any management scheme. If you wait until > it's reused, you might as well forgo the advantages of TRIM/UNMAP. If > a the controller wants to coalesce, let it coalesce. I'm sorry, you're wrong. There is a tradeoff point, and it's different for each drive model. Sending down a steady stream of tiny TRIMs is going to give terrible performance. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- 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