From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx130.postini.com [74.125.245.130]) by kanga.kvack.org (Postfix) with SMTP id 347B56B004D for ; Sun, 22 Jan 2012 17:12:15 -0500 (EST) Message-ID: <4F1C897A.3070401@panasas.com> Date: Mon, 23 Jan 2012 00:11:06 +0200 From: Boaz Harrosh MIME-Version: 1.0 Subject: Re: [Lsf-pc] [LSF/MM TOPIC] [ATTEND] Future writeback topics References: <4F1C141C.2050704@panasas.com> <1327243783.2834.6.camel@dabdike.int.hansenpartnership.com> <4F1C2D45.4090208@panasas.com> <1327247393.2834.15.camel@dabdike.int.hansenpartnership.com> In-Reply-To: <1327247393.2834.15.camel@dabdike.int.hansenpartnership.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: James Bottomley Cc: Andrea Arcangeli , Wu Fengguang , Jan Kara , "Martin K. Petersen" , linux-scsi , Dave Chinner , linux-fsdevel , lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org On 01/22/2012 05:49 PM, James Bottomley wrote: > > But this topic then becomes adding alignment for non block backed > filesystems? I take it you're thinking NFS rather than MTD or MMC? > Sorry to differ. But no this is for most making the IO aligned in the first place. Block-dev or not. Today VFS has no notion of alignment and IO is submitted as is with out any alignment considerations. > For multiple devices, you do a simple cascade ... a bit like dm does > today ... but unless all the devices are aligned to optimal I/O it never > really works (and it's not necessarily worth solving ... the idea that > if you want performance from an array of devices, you match > characteristics isn't a hugely hard one to get the industry to swallow). > No I'm talking about raid configurations like object raid in exofs/NFS or raid0/5 in BTRFS and ZFS and such, where there are other larger alignment structures to consider. Also for large-blocks filesystems/devices who would like IO aligned on bigger than a page sizes. Thanks Boaz -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org