Re: [2.4.17/18pre] VM and swap - it's really unusable

David Weinehall
2002-01-10T19:37:50Z

On Thu, Jan 10, 2002 at 01:34:17PM -0500, Chris Friesen wrote:
> Rob Landley wrote:
>
> > And a sound card with only 1mS of buffer in it is definitely not useable on
> > windoze, the minimum buffer in the cheapest $12 PCI sound card I've seen is
> > about 1/4 second (250ms). (Is this what you mean by "hardware fun"?) Even
> > if the app was taking half that, it's still a > 100ms big gap where the OS
> > leaves it hanging before you get a dropout. (Okay, some of that's watermark
> > policy, not sending more data to the card until half the buffer is
> > exhausted...) What sound output device DOESN'T have this much cache?
>
> Imagine taking an input, doing dsp-type calculations on it, and sending it back
> as output. Now...imagine doing it in realtime with the output being fed back to
> a monitor speaker. Think about what would happen if the output of the monitor
> speaker is 1/4 second behind the input at the mike. Now do you see the
> problem? A few ms of delay might be okay. A few hundred ms definately is not.
>
> > Now VIDEO is a slightly more interesting problem. (Or synchronizing audio
> > and video by sending really tiny chunks of audio.) There's no hardware
> > buffer there to cover our latency sins. Then again, dropping frames is
> > considered normal in the video world, isn't it? :)
>
> If I'm trying to watch a DVD on my computer, and assuming my CPU is powerful
> enough to decode in realtime, then I want the DVD player to take
> priority--dropping frames just because I'm starting up netscape is not
> acceptable.

Ummm, and you couldn't consider refraining from firing up Netscape
while watching the DVD, could you?!

I get your point, but the example was poorly chosen, imho.

Regards: David Weinehall
_ _
// David Weinehall <tao@acc.umu.se> /> Northern lights wander \\
// Maintainer of the v2.0 kernel // Dance across the winter sky //
\> http://www.acc.umu.se/~tao/ </ Full colour fire </