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Re: [vox-tech] Skipping sound
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Re: [vox-tech] Skipping sound

I managed to hack around the problem; I installed XFree86 3.3.6 on this
machine, and I can no longer make the music skip just by causing a lot
of screen updates. 

I suspect this is a bug in XFree 4's mga driver, and I will be sending
in a bug report this weekend. 

Thanks for everyone's advice. 

On Thu, Feb 27, 2003 at 08:29:55PM -0500, Mike Simons wrote:
> On Thu, Feb 27, 2003 at 03:03:22PM -0800, Samuel Merritt wrote:
> > > > > If I have music playing and I move a window around, switch windows, or
> > > > > scroll a window, the music stutters. I'm using XFree86 4.2.1 and ALSA
> > > > > 0.9.0rc2 (defaults for Mandrake 9). 
> ===
> latency_multiplier   8
> min_grant_clocks  72, max_latency_clocks    0
> min_grant_clocks   0, max_latency_clocks  640
> min_grant_clocks  16, max_latency_clocks  192
> min_grant_clocks   0, max_latency_clocks    0
> min_grant_clocks 160, max_latency_clocks  320
> min_grant_clocks 128, max_latency_clocks  272
> sum of minimum grants 376
> lowest latency allowed 192
> ====
>   According to that last URL your situation is hopeless,
> because the sound device says it can't wait more than 
> 192 ticks, before being serviced and if the guy with 
> 160 and 128 happen to come along the sound card has hard 
> to wait too long.
>   I personally think that is bogus... there has got to be a way to have
> them play along.
>   I don't expect this to work... but try it and let me know what the
> results are:

You were right; it didn't work. I ran those commands below. I also
experimented with low latencies; with a latency_timer of 20 (32 decimal)
for all devices, the stuttering was slightly worse. A latency_timer of
32 for everything but the video card, and a latency_timer of ee for the
video card improved matters a tiny bit. 

I chose ee, not ff, because the URL below suggests that decimal 248 is
the maximum possible setting for the latency timer. I did try ff for the
video card, but it didn't seem to help.

It should be noted that the stuttering still occurred with the network
cable unplugged, so I don't think it's a problem with the network card
hogging the bus. 

> ====
> # "open up" the PCI bus by allowing fairly long bursts for all devices,
> # increasing performance
> setpci -v -d *:* latency_timer=b0
> # maximize latency timers for network and audio, allowing them to transmit
> # more data per burst, preventing buffer over/underrun conditions
> setpci -v -s 02:04.0 latency_timer=ff  
> setpci -v -s 02:06.0 latency_timer=ff
> ===
> that advice comes from the following URL:
>   http://www-106.ibm.com/developerworks/library/l-hw2.html
>   Basically if it doesn't work I'd like to try some other settings.
>     Let me know,
>       Mike
> ps: it's remotely possible your machine will lockup when you run those
> set PCI commands, so be sure to save anything important.
> _______________________________________________
> vox-tech mailing list
> vox-tech@lists.lugod.org
> http://lists.lugod.org/mailman/listinfo/vox-tech

Samuel Merritt
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