Re: [Jack-Devel] new IIO driver added to jack - large overruns

OK, thanks.

I am now compiling with different flags on the ARM (let me know if you 
need them) ... and I have removed this xrun problem from the ALSA 
driver. I have also drastically reduced the xrun problem in the iio 
driver to about 0.3 ms. The xruns occur about every 43 ms. This result 
occurs when I sample 4 channels at 1 MHz.
If I only sample 2 channels I find I get xruns of about 0.15 ms. This 
occurs roughly every 67 ms.

By the way - in a similar manner to jack2 - I find I need to remove the 
POST_PACKED_STRUCTURE for the ARM architecture... otherwise I get the 
expected "Bus error" ... hmmm.

I am wondering what I should do to squeeze the tiny 0.3 ms speed up !

If you want to help, then you can pull the gtkiostream and flatmax/jack1 
repos. thanks

Here is an example run :

# jackd -R -d iio -p2048

created iio driver ... iio_pcm|1000000|2048|2048|4|0

**** iio: xrun of 6099u usec last xrun was 8147us ago.
**** iio: xrun of 21u usec last xrun was 34837us ago.
**** iio: xrun of 326u usec last xrun was 43334us ago.
**** iio: xrun of 326u usec last xrun was 43334us ago.
**** iio: xrun of 252u usec last xrun was 43260us ago.
**** iio: xrun of 252u usec last xrun was 43260us ago.
**** iio: xrun of 253u usec last xrun was 43261us ago.
**** iio: xrun of 270u usec last xrun was 43278us ago.
**** iio: xrun of 253u usec last xrun was 43261us ago.
**** iio: xrun of 252u usec last xrun was 43260us ago.
**** iio: xrun of 252u usec last xrun was 43260us ago.
**** iio: xrun of 289u usec last xrun was 43297us ago.
**** iio: xrun of 290u usec last xrun was 43298us ago.
**** iio: xrun of 252u usec last xrun was 43260us ago.
**** iio: xrun of 252u usec last xrun was 43260us ago.
**** iio: xrun of 326u usec last xrun was 43334us ago.
**** iio: xrun of 271u usec last xrun was 43279us ago.
**** iio: xrun of 252u usec last xrun was 43260us ago.
**** iio: xrun of 308u usec last xrun was 43316us ago.


Matt

On 21/01/14 00:12, Paul Davis wrote:
>
>
>
> On Mon, Jan 20, 2014 at 4:55 AM, Matt Flax <[hidden] 
> <mailto:[hidden]>> wrote:
>
>     Just confirming that I also see a similar xrun when running the
>     alsa driver ... see below ...
>     It is possible that this problem is within Jack itself, and not
>     the drivers ...
>
>
> xruns are caused by systemic problems or by clients, not by JACK itself.
>
>
> **** alsa_pcm: xrun of at least 71.259 msecs
>
> **** alsa_pcm: xrun of at least 71.001 msecs
>
> **** alsa_pcm: xrun of at least 71.038 msecs
>
> **** alsa_pcm: xrun of at least 71.019 msecs
>
>
> the consistency of the timing strongly suggests a systemic cause 
> (there are many possible such causes)
>
>

1390290479.10492_0.ltw:2,a <52DE261A.1050909 at flatmax dot org>