Subject: [linux-audio-dev] Re: [Alsa-devel] Re: more bad low latency results
From: Takashi Iwai (tiwai_AT_suse.de)
Date: Thu Nov 15 2001 - 19:48:45 EET
At Thu, 15 Nov 2001 18:16:44 +0100,
Maarten de Boer wrote:
>
> > I've used this setting:
> >
> > echo 6 > /proc/sys/vm/vm_scan_ratio
> > echo 2 > /proc/sys/vm/vm_mapped_ratio
> > echo 4 > /proc/sys/vm/vm_balance_ratio
>
> Uuhh... I don't have these files...
> $ ls /proc/sys/vm/
> bdflush kswapd overcommit_memory page-cluster pagetable_cache
>
> Did I miss something in my kernel configuration?
Oops, sorry, they are still in AA kernel only..
Or, will you try AA patches? It's not a bad idea, since the current
(vanilla) VM is based on Andrea's code. Linus still doesn't include
all his patches. Maybe my 2.4.13 LL patches at
ftp.suse.com/pub/people/tiwai/suse-patches can be applied without
rejection.
> > That's really weird.. How about to measure the time of read/write
> > responce in latency.c so that we can know at least whether it's
> > related with the kernel latency.
>
> It's a different problem. The alsa capture adds random values at
> random places (not periodically as for a I can see) in a way that
> it sounds like a dusty vinyl record. This doesn't happen when I
> use arecord, it only happens with the alsa-lib/test/latency. I write
> each captured buffer to disk, and the random values are clearly
> visible (and hearable). It happens both in non-block and in poll mode.
Hmm sounds like h/w problem, then..
It's interesting to know where the data is contaminated, whether on
the driver level or transfer between capture and playback on
user-space, or what else..
Takashi
This archive was generated by hypermail 2b28 : Thu Nov 15 2001 - 19:46:09 EET