need a tweak

Jason jkenner@mindspring.com
Sun, 05 Nov 2000 23:46:18 -0700


> What type of sound card do you have?  I'm not an expert on the matter,
> but I think that there are some which are more resource friendly
> than others.  You may also want to try out the ALSA drivers instead
> of the ones provided by default with the kernel.

ISA sound can be a problem here, as the ISA bus is only 8MHz in most
machines. And unfortunately, the option to overclock the ISA bus is
missing from most pentium class systems - the PCI/ISA divisor has
become fixed at 4... so no more 20MHz ISA bus like on the X5 mentioned
below (I remember people amazed at the performance I was getting out
of a 1MB trident ISA video card... heheh)

The problem is that some chipsets have a way of stalling things while
the ISA bus is being used, particularly when DMA channels are
involved.

> Though it seems unlikely, another potential bottleneck could be your
> disk.  (If you're not able to feed the mp3 decoder quick enough, it'll
> be choppy.)  You may wish to play around with hdparm.

I starting using a 16M ramdisk to play MP3 back when I was powering my
system with a 160MHz AMD X5 (79.9 BogoMIPS). I stopped using it when I
got a faster processor due to the fact that using the ramdisk casued
the dreaded 16M ISA DMA problem and necessary cold boot solution,
until persistant DMA buffers was introduced with kernel 2.2 - since
that point, I've started using the ramdisk again, and found that it
doesnt make much difference one way or the other, due to the way linux
handles cache - cat'ing the file to /dev/null before playing may be
just as effective.



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