From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Fw: framebuffer blitting performance loss 2.6.12 -> 2.6.13-rc3 Date: Fri, 15 Jul 2005 03:39:12 -0700 Message-ID: <20050715033912.1cd9b6c3.akpm@osdl.org> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1DtNbz-0003BF-9K for linux-fbdev-devel@lists.sourceforge.net; Fri, 15 Jul 2005 03:40:07 -0700 Received: from smtp.osdl.org ([65.172.181.4]) by sc8-sf-mx1.sourceforge.net with esmtps (TLSv1:DES-CBC3-SHA:168) (Exim 4.44) id 1DtNbx-0008Gp-U4 for linux-fbdev-devel@lists.sourceforge.net; Fri, 15 Jul 2005 03:40:07 -0700 Sender: linux-fbdev-devel-admin@lists.sourceforge.net Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: linux-fbdev-devel@lists.sourceforge.net Cc: Knut Petersen Begin forwarded message: Date: Fri, 15 Jul 2005 12:14:37 +0200 From: Knut Petersen To: linux-kernel@vger.kernel.org Subject: framebuffer blitting performance loss 2.6.12 -> 2.6.13-rc3 Hi everybody! There is a serious performance loss between 2.6.12 and 2.6.13-rc3 affecting _all_ framebuffer devices, especially those with fast bitblit functions. System: Via Epia 5000 CPU: Via Samuel 2, 533MHz Graphics core: Cyberblade/i1 (Blade 3D core integrated in 8601A) Framebuffer driver: Not yet released fully accelerated framebuffer driver cyblafb Test setup ========== video mode: 1280x1024, vyres=2662, bpp=8, 8x16 font, ypan scrollmode kernel 2.6.13-rc3 is compiled with HZ==1000 Measurement 1: Compile framebuffer modules Result: 2.6.13-rc3 is slightly slower, but this is an almost invisible performance loss of about 1% Measurement 2: time cat of file consisting of 2000 empty lines Result: | 2.6.12 / 2.6.13-rc3 ------------------------------------------+---------------------- total time | 0.182s / 0.220s Measurement 3: time cat of file consisting of 2000 full lines of 160 characters each. Result: Result: | 2.6.12 / 2.6.13-rc3 ------------------------------------------+---------------------- total time | 0.853s / 1.062s time spent in framebuffer bitblit routine | 0.256s / 0.257s time spent for kernel bitblit overhead | 0,426s / 0.623s !!! other time (scrolling, disk io etc) | 0,171s / 0,182s Discussion of measurements ========================== Framebuffer compiling shows that the general kernel performance is more or less unchanged between 2.6.12 and 2.6.13-rc3. Cat-ing of the file consisting of 2000 empty lines takes about 20.9% more time, cat-ing of the file consisting of 2000 full lines takes about 24% more time. As the time spent in the bitblit function of the framebuffer driver does not change I do assume that the data sent to the framebuffer driver has not changed. But the new routines take about 46% longer. All framebuffer drivers should be affected by this performance loss, but the faster the bitblit of the used framebuffer driver is, the more it will affect the general performance. You will not see such a great difference if e.g. vesafb is used. Please have a serious look at the changed code of fbcon/fbmem etc or switch back to the old routines. cu, Knut - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click