From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261181AbUEXG6i (ORCPT ); Mon, 24 May 2004 02:58:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261184AbUEXG6h (ORCPT ); Mon, 24 May 2004 02:58:37 -0400 Received: from smtp101.mail.sc5.yahoo.com ([216.136.174.139]:45481 "HELO smtp101.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S261181AbUEXG6g (ORCPT ); Mon, 24 May 2004 02:58:36 -0400 Message-ID: <40B19D15.1090105@yahoo.com.au> Date: Mon, 24 May 2004 16:58:29 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040401 Debian/1.6-4 X-Accept-Language: en MIME-Version: 1.0 To: Ingo Molnar CC: Con Kolivas , Billy Biggs , Kernel Mailing List Subject: Re: tvtime and the Linux 2.6 scheduler References: <20040523154859.GC22399@dumbterm.net> <200405240254.20171.kernel@kolivas.org> <20040524084334.GB24967@elte.hu> In-Reply-To: <20040524084334.GB24967@elte.hu> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > * Con Kolivas wrote: > > >>> 33 ms : time per NTSC frame >> >>snip >> >>The followup email from someone describing good performance may help >>us understand what's going on. Your example of poor performance is one >>when the cpu performance is marginal to get exactly 30 fps processed >>and on the screen. The cpu overhead in 2.6 is slightly higher than 2.4 >>so a borderline case may be just pushed over. > > > most of the cpu overhead comes from HZ=1000. Especial with SCHED_FIFO > there should be minimal (if any) impact from the scheduler changes - > SCHED_FIFO tasks get all CPU time, no ifs and whens. > > could people who experience tvtime performance problems apply the patch > below to change HZ back to 100? Does it have any impact? > Just one other thing - realtime scheduling was basically broken up until around 2.6.5. Before starting any tests, please ensure first that you are using at least the 2.6.5 kernel. Thanks.