[Jack-Devel] high sample rates cause unknown client xruns

Hi there,

I am experiencing problems with high sample rates when using jack.

Whilst the driver is more then capable of reading data at high sample 
rates, it seems that the client falls over when it tries to interact.

I have created a very simple dummy driver :
https://github.com/flatmax/jack1/blob/master/drivers/iio/iio_driver_dummy.C

When the definition IIO_DEFAULT_READ_FS is set to 48000  it works ok.
When the definition IIO_DEFAULT_READ_FS is set to 1000000  it generates 
client based xruns ... when using jack_rec ...

I guess this is to be expected ... however I didn't think the internal 
glue between clients and servers was going to be so heavy.

I start the server like so :
jackd -r -d iio -i 4

I would think that jack_rec shouldn't have a problem dumping fast to 
/dev/null ...

On a desktop the following works :
$ jack_rec -f /dev/null -B 4096 -d 1 system:capture_1 system:capture_2

On a desktop the following fails :
$ jack_rec -f /dev/null -B 2048 -d 1 system:capture_1 system:capture_2
disk thread finished
jackrec failed with 977 overruns.
  try a bigger buffer than -B 2048.


On an ARM core, neither works ! Even very large buffer sizes.

Matt

1392100923.13839_0.ltw:2,a <52F9C558.4010709 at flatmax dot org>