From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arthur Marsh Subject: Re: MIDI playback not keeping steady time with recent kernels Date: Wed, 09 Feb 2011 11:21:26 +1030 Message-ID: <4D51E50E.8000703@internode.on.net> References: <559v18-575.ln1@ppp121-45-136-118.lns11.adl6.internode.on.net> <11c228-725.ln1@ppp121-45-136-118.lns11.adl6.internode.on.net> <4D512EA9.2020909@ladisch.de> <4D515EFD.3040909@internode.on.net> <4D5163D8.8010708@ladisch.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from ipmail05.adl6.internode.on.net (ipmail05.adl6.internode.on.net [150.101.137.143]) by alsa0.perex.cz (Postfix) with ESMTP id E4112244B8 for ; Wed, 9 Feb 2011 01:51:48 +0100 (CET) In-Reply-To: <4D5163D8.8010708@ladisch.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Clemens Ladisch Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Clemens Ladisch wrote, on 09/02/11 02:10: > Arthur Marsh wrote: >> OK, I applied this patch. >> >> When the MIDI file was playing: >> I still experienced some slow-down and speed-up under heavy load. > > Is "some" less than previously? The amount of slow-down appears to be less than previously. > > It shouldn't be possible to get a speed-up; this looks as if your > computer's clock is not stable. Are you using an NTP daemon? To clarify, the speed-up is back to original tempo, and yes I'm using an NTP daemon. There has been an issue of the pc not keeping accurate time under GNU/Linux even with ntpd running and using an NTP server a few hops away. > > What kind of heave load is this? Does the same happen if you execute > "yes | tail" in a shell? The load when I experienced this problem was about 4 or 5, and mainly seemed to be tied to activities that caused swapping (e.g. running aptitude -u when other applications were using all available memory and some swap). After quitting some applications so that there was no swapping going on (kswapd0 showing 0.0 cpu), the MIDI file played fine, even with "yes|tail" running. Adding aptitude -u to the mix, which resulted in kswapd0 running at 4 to 10 percent cpu, caused a slow-down. > > > Regards, > Clemens > Thanks again, Arthur.