From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?B?SsO2cm4=?= Engel Subject: Re: [PATCH] LogFS take three Date: Wed, 16 May 2007 13:23:17 +0200 Message-ID: <20070516112317.GB5472@lazybastard.org> References: <20070515151919.GA32510@lazybastard.org> <20070515133759.9ee434a2.akpm@linux-foundation.org> <20070516000630.GD1220@lazybastard.org> <20070516052253.GI943@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, Albert Cahalan , Thomas Gleixner , Jan Engelhardt , Evgeniy Polyakov , Pekka Enberg , Greg KH , Ingo Oeser To: Willy Tarreau Return-path: Received: from lazybastard.de ([212.112.238.170]:39949 "EHLO longford.lazybastard.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756182AbXEPL1i (ORCPT ); Wed, 16 May 2007 07:27:38 -0400 Content-Disposition: inline In-Reply-To: <20070516052253.GI943@1wt.eu> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Wed, 16 May 2007 07:22:54 +0200, Willy Tarreau wrote: >=20 > On hard disks, yes, but as you suggested, there are lots of other fla= sh > devices interfaced as block devices. CompactFlash comes to mind, USB > keys too. And on these ones, the most important is to reduce the numb= er > of writes and to support large sizes. I already see LogFS as an inter= esting > alternative to JFFS2 on such devices, eventhough it does not (yet?) s= upport > compression. It does support compression now. That part was finished, erm, about tw= o weeks ago. Logfs on Smartmedia format (I assume most CompactFlash, USB, SD and MMC media use that) will currently cause a nasty interaction. Unlike JFFS2= , logfs will alternately write to several eraseblocks. On real flash, alternating between half-finished blocks is free. Smartmedia standard requires to finish the last block before moving to the next. So the logfs write pattern will cause it to add an erase/write overhead of - depending on erase size and compression - 4x to 512x. Pretty bad. If Smartmedia was really stupid, there would be no overhead at all. An= y manucaturers listening should seriously think about allowing raw flash access to their devices. ;) J=C3=B6rn --=20 To recognize individual spam features you have to try to get into the mind of the spammer, and frankly I want to spend as little time inside the minds of spammers as possible. -- Paul Graham - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html