From alsa-devel-owner@alsa.jcu.cz  Mon Oct  5 14:36:56 1998
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From: Guenter Geiger <guenter.geiger@psp-vie.be.philips.com>
To: "alsa-devel@jcu.cz" <alsa-devel@jcu.cz>,
        "'Thomas Sailer'"
	 <sailer@ife.ee.ethz.ch>
Subject: RE: PCM mixing draft v0.2
Date: Mon, 5 Oct 1998 14:36:21 -0700
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Is it possible to access user memory from within interrupts routines?
If it were possible, all audio queues could be held in userland and the driver just fills the (relatively small)
dma buffers.  Does that make any sense to anybody ?

G

----------
From:  Thomas Sailer[SMTP:sailer@ife.ee.ethz.ch]
Sent:  Monday, October 05, 1998 4:49 AM
To:  alsa-devel@jcu.cz
Subject:  Re: PCM mixing draft v0.2

Jaroslav Kysela wrote:

> OK. Looks like main problem is good scheduler. I see that in both cases is
> main delay caused by task scheduler now. Current Linux scheduler is
> probably limited with system clock (100Hz on i386). This means that delay
> should be up to 20ms (or I missed something?). Other delay should be added
> by effects, filters, conversions etc, but this must be done in both cases.

I don't quite see what problems ppl have with the Linux scheduler.
The basic sched tick is indeed 100Hz on i386, but that doesn't mean
it can only reschedule at 10ms boundaries. If your driver wants it,
Linux can also reschedule at the end of a sound driver interrupt for
example (see the need_resched stuff).

Tom
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