From alsa-devel-owner@alsa.jcu.cz  Sat Mar 13 16:40:16 1999
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Date: Sat, 13 Mar 1999 17:05:20 +0200 (EET)
From: Ville Syrjala <villes@syrjala.pp.sci.fi>
To: alsa-devel@alsa.jcu.cz
Subject: Re: Enlarging the dma buffer for audiopci
In-Reply-To: <19990313131517.A2076@gotss.ml.org>
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On Sat, 13 Mar 1999, Kerry Hoath wrote:

> If your system has IDE disks try ide interupt unmasking with hdparm and enabling
> multiple sector mode. Often "load" is the system reading and writing lots of
> stuff to and from disks. If you unmask the ide nterrupts you can get better
> interrupt latency for the sound drivers, and you can aslo have better system
> responsiveness. I use
> hdparm -u1 -m8 /dev/hda

I use this too. My commandline looks like this "hdparm -X66 -u 1 -c 1 -d 1
/dev/hda". I didn't get audio dropouts while playing xheretic w/ sound, 
doing a couple of "find /"s (3 Fat32 and one Ext2 partition each over 2 
GB), compiling the kernel "make -j 12 zImage" and a SSH connection running 
pine all at the same time while playing mp3s with X11AMP. Of course the 
explanation could be my 450 MHz Celeron and/or UDMA Quantum Fireball EL. I
didn't event have multcount set but I can set it to 16, which should 
improve performance even more.

> on my ide systems and I often increase sound interrupt priority with irqtune.
> Regards, Kerry.
> On Fri, Mar 12, 1999 at 03:18:34PM +0100, T.Mertes@mobilkom.at wrote:
> > Hello
> > 
> > I have a SB 128 PCI sound card that i am using with
> > linux 2.2.3 and the ALSA sound driver "audiopci".
> > 
> > I have sound dropouts when playing wave files under load.
> > It comes from the fact that the program which plays
> > (sox, play, ...) has to wait sometimes (because of the
> > load) at the read() for too long. While the program waits, the
> > 128kB buffer of the driver runs out and there is a dropout.
> > 
> > This seems to be really a buffer problem, because I have it
> > also with the sound driver from the kernel and with the
> > SB 16 vibra sound card.
> > 
> > I know that there are other ways to solve the problem.
> > (sound demon/playing program which use threads and
> > big buffers.) But I want first to investigate possibilitys to
> > repair the problem on the device driver side.
> > 
> > There are two possibilities here:
> > 
> >   1. The sound driver does not use its 128kB efficient
> >       (After issuing a write() the buffer should always be
> >       almost full). I do not think that this is the case,
> >       but I would be happy if the driver writer would check
> >       this also.
> > 
> >   2. A buffer of 128kB is too small (I think this is the case).
> >       I would like to enlarge the buffer (I have to try out,
> >       which buffer size is necessary). The current audiopci
> >       driver limits the size of the dma buffer to at most 128k.
> > 
> > My question is:
> > 
> >   - Is it possible to enlarge the buffer of the audiopci driver
> >     to even several megabytes (configurabel like it is now).
> >   - Is there a built in ALSA or PCI-DMA limit which
> >     prohibits it? Can we lift this limit?
> >   - What is necessary to do to enlarge the buffer
> >     (a patch would be great :-) ).
> > 
> > 
> > Greetings Thomas
> > 
> > ------
> > To unsubscribe from <alsa-devel@alsa.jcu.cz> mailing list send message
> > 'unsubscribe' in the body of message to <alsa-devel-request@alsa.jcu.cz>.
> > 
> 
> -- 
> --
> Kerry Hoath:
> kerry@gotss.spice.net.au or khoath@lis.net.au
> ICQ UIN: 8226547
> 
> ------
> To unsubscribe from <alsa-devel@alsa.jcu.cz> mailing list send message
> 'unsubscribe' in the body of message to <alsa-devel-request@alsa.jcu.cz>.
> 

---
Ville Syrjl
syrjala@sci.fi
http://www.sci.fi/~syrjala/


