From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with archive (Exim 4.43) id 1OTHcM-00081D-D5 for mharc-grub-devel@gnu.org; Mon, 28 Jun 2010 12:55:34 -0400 Received: from [140.186.70.92] (port=37469 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OTHcB-0006ye-8R for grub-devel@gnu.org; Mon, 28 Jun 2010 12:55:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OTHbt-0007Pf-Dg for grub-devel@gnu.org; Mon, 28 Jun 2010 12:55:06 -0400 Received: from smarthost02.mail.zen.net.uk ([212.23.3.141]:51016) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OTHbt-0007PV-9E for grub-devel@gnu.org; Mon, 28 Jun 2010 12:55:05 -0400 Received: from [82.69.40.219] (helo=riva.pelham.vpn.ucam.org) by smarthost02.mail.zen.net.uk with esmtp (Exim 4.63) (envelope-from ) id 1OTHbr-00013H-7e; Mon, 28 Jun 2010 16:55:03 +0000 Received: from cjwatson by riva.pelham.vpn.ucam.org with local (Exim 3.36 #1 (Debian)) id 1OTHbq-0005hz-00; Mon, 28 Jun 2010 17:55:02 +0100 Date: Mon, 28 Jun 2010 17:55:02 +0100 From: Colin Watson To: Colin D Bennett Message-ID: <20100628165502.GC21862@riva.ucam.org> References: <20100625085834.GM21862@riva.ucam.org> <20100628094021.77b3667f@svelte> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100628094021.77b3667f@svelte> User-Agent: Mutt/1.5.18 (2008-05-17) X-Originating-Smarthost02-IP: [82.69.40.219] X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) Cc: The development of GNU GRUB Subject: Re: [RFC] Hacky MTRR support X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Jun 2010 16:55:32 -0000 On Mon, Jun 28, 2010 at 09:40:21AM -0700, Colin D Bennett wrote: > On Fri, 25 Jun 2010 09:58:34 +0100 > Colin Watson wrote: > > I recently posted ("Subject: [PATCH] Optimise memset on i386" - > > sorry, I don't seem to have a route to lists.gnu.org at the moment so > > I can't post an archive link) about optimising GRUB's video > > initialisation, and hinted that it might be possible to do better by > > implementing MTRRs as well in order to allow the system to combine > > writes to video memory rather than taking a cache stall for every > > single write. I can report that, at least on the hardware I was > > using, it does make a significant difference: filling the screen with > > solid colour now takes 10 milliseconds rather than 160! This ended > > up shaving about a second off the boot time of the project I'm > > working on. > > In addition to the improved startup speed, I see the potential for a > huge increase in graphical menu responsiveness if caching is enabled. > Would framebuffer draw and image blitting performance be improved by > using write-combining with MTRRs? I didn't benchmark that, but I'd be pretty surprised if it weren't improved. -- Colin Watson [cjwatson@ubuntu.com]