USB Soundcard: sound stops when system under load

kenobi · n00b Joined: 27 Nov 2002 Posts: 10

Hi!

I have the Sennheiser PC155USB Headset.
I'm running 2.6.11-gentoo-r4 on a Dual Athlon MP 1900+ system and have snd-usb-audio running as a module. OSS Emulation is not running, only alsa.

Sound works ok as long as I don't do too much.
When I copy a big file from a to b, burn something or download at a high rate(like >5mb) then my sound just stops.
In xmms (with alsa drivers) I get about half a second of sound each time I press on start. Same thing with mplayer running with alsa drivers (no OSS).I'll have to wait till the operation finishs.

Does anyone experience similar problems?
Any suggestions?

Thanks,

kenobi

palmer · Guru Joined: 17 Nov 2004 Posts: 322 Location: Berkeley, CA

I believe this is a limitation of USB

The problem is that USB bandwidth is tied to your processor
Something that transfers a lot of data over USB will use ~15-20% of your processor speed

Is there some way to run alsa at a lower nice level (try -5, or -10)
Try running other things at a higher nice lever (try 5 or 10)

This is the one thing that is keeping me from buying a USB sound card

-palmem

m00dawg · Posted: Sun May 22, 2005 5:31 pm Post subject:

You could also try to see how much cpu usage your soundcard generates by running top when you are playing an mp3 in xmms (on an otherwise idle system). You could also try to up the bufers in xmms, although if the problem is related to the USB system itself, it may only marginally help. Also, if you aren't using USB 2.0, I would consider either upgrading the motherboard or buying a USB 2.0 PCI card. Since USB 1.1 tops out at 11mps (bits, not bytes) or something of that sort and USB 2.0 runs at 480mbp, it is a big differences
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kenobi · n00b Joined: 27 Nov 2002 Posts: 10

Thanks for your hints!

Unfortunately changing the nice level of mplayer/xmms didn't help and I don't see how I could change alsa's nice level.
But I realised something else...sound is ok when I don't use my sata harddrive. So it seems to be a problem with sata_sil.
Might be because I have a seagate drive for which there is some strange fix in the driver to make it work at all, with bad performance anyway.

m00dawg · Posted: Mon May 23, 2005 3:50 am Post subject:

Well, one way to test it is to run something loke bonnie++ (filesystem benchmarking program) or just copy a bigass file from one directory to another and then run top to see what CPU % it is pulling. bonnie will also give you a fair amount of feedback with regards to your filesystem performance, although you generally need a basis for comparison to see the speed issues.

One possible thing you could try, and I'm not sure if it'll help with SATA stuff (haven't been fortunate enough to get a SATA drive yet) would be to play with hdparm and see what kind of info it is giving you. Perhaps your drive isn't set at it's fastest setting or DMA isn't enabled or something of that sort. I noticed when I forgot to load the correct module for my chipset, my performance dropped like a rock (both in terms of filesystem and cpu usage). So perhaps you could try that. No idea how things roll with hdparm and SATA, but it's worth a look?
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