From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261401AbVGOKOS (ORCPT ); Fri, 15 Jul 2005 06:14:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261765AbVGOKOS (ORCPT ); Fri, 15 Jul 2005 06:14:18 -0400 Received: from mailout05.sul.t-online.com ([194.25.134.82]:2462 "EHLO mailout05.sul.t-online.com") by vger.kernel.org with ESMTP id S261401AbVGOKOQ (ORCPT ); Fri, 15 Jul 2005 06:14:16 -0400 Message-ID: <42D78C8D.4040009@t-online.de> Date: Fri, 15 Jul 2005 12:14:37 +0200 From: Knut Petersen User-Agent: Mozilla/5.0 (X11; U; Linux i686; de-AT; rv:1.7.7) Gecko/20050414 X-Accept-Language: de, en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: framebuffer blitting performance loss 2.6.12 -> 2.6.13-rc3 X-Enigmail-Version: 0.86.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-ID: bNeEgwZJoeOjl+2evlg23gCoF7um-9OwzKQ940WfT5YuzdyNDZETkD@t-dialin.net X-TOI-MSGID: 7768efae-da78-46b4-aedd-c436c4c164b3 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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