Subject: Re: [linux-audio-dev] Sequencer Sync Woes
From: Paul Davis (pbd_AT_Op.Net)
Date: Tue Feb 06 2001 - 18:54:17 EET
> I first just assuming that for every read(), exactly rtc::hz time
>passed. This wasn't great, since you get pileups more often than I
>thought. I have a P3-700, and just switching desktops caused skips.
if you install a low latency kernel, you can almost guarantee no skips
(unless by desktops you mean between VT's; this is a known bottleneck
in the kernel; X WM desktop switching won't cause them). CPU speed
makes very little difference to all this, BTW.
> Now I use the RTC code just for throttling, and call gettimeofday to
>check the actual time (as you suggested). This seems 'acceptable'. I
you could also use the cycle timer - using the RTC is (currently)
intel only anyway, so adding calls to rdtscl() shouldn't hurt. its
about 12 usecs instead of 60-200usecs for gettimeofday.
>can only make it skip by ls -lR'ing my drive (this seems ridiculous, but
IDE ? are the drivers tuned "correctly" ?
> Would it be worthwhile to create a new kernel module for doing a
>sequencer intermediary? Just an interface to /dev/midi* with
>timestamps.
don't go there :) sounds like a nice simple step right ? next thing
you know, you'll have reinvented the ALSA sequencer, and your version
will likely have even less documentation.
--p
This archive was generated by hypermail 2b28 : Tue Feb 06 2001 - 19:07:34 EET