From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaohua Li Subject: Re: [PATCH v3 0/5]add new ioctls to do metadata readahead in btrfs Date: Thu, 20 Jan 2011 10:27:13 +0800 Message-ID: <1295490433.1949.886.camel@sli10-conroe> References: <1295399715.1949.863.camel@sli10-conroe> <20110119123451.75bb3c76.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: David Nicol Cc: Andrew Morton , "linux-btrfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Chris Mason , Christoph Hellwig , Arjan van de Ven , "Yan, Zheng" , "Wu, Fengguang" , linux-api , manpages List-Id: linux-api@vger.kernel.org On Thu, 2011-01-20 at 05:33 +0800, David Nicol wrote: > On Wed, Jan 19, 2011 at 2:34 PM, Andrew Morton > wrote: > > > It would be much more valuable if those 3.5 seconds were available to > > devices which really really care about bootup times, but very few of > > those devices use rotating disks nowadays, I expect? > > And don't rotating disk modules read and buffer whole tracks, doing > their own readahead, anymore, anyway? Isn't that part of what "on-disk > cache" does? The disk readahead and the metadata readahead is completely different, you didn't even look at the patch or log before saying this.