On Thu, 11 Jul 2013, James Stone wrote: > Hi Clemens, > > On Mon, Jul 8, 2013 at 2:12 PM, James Stone <jamesmstone@xxxxxxxxx> wrote: > <Snip!> > >> Acquire audio card Audio0 > >> creating alsa driver ... hw:USB,0|-|64|2|44100|0|0|nomon|swmeter|-|16bit > >> Using ALSA driver USB-Audio running on card 0 - Focusrite Scarlett 2i4 > >> USB at usb-0000:00:12.2-3, high speed > >> configuring for 44100Hz, period = 64 frames (1.5 ms), buffer = 2 periods > >> ALSA: final selected sample format for playback: 32bit integer little-endian > >> ALSA: use 2 periods for playback > >> ALSA: poll time out, polled for 2176094 usecs > >> JackAudioDriver::ProcessAsync: read error, stopping... > >> > >> This is a definite reduction in performance compared to earlier kernels. > >> > > > > Some further info - on 3.5.0-28, I can start jackd in playback only > > with 8 frames/period, and capture only at 16 frames/period. > > > > Any thoughts on further investigating this bug with the 3.8.0 kernel > with the Focusrite Scarlett 2i4? I'm happy to continue with any > further testing if it would be helpful.. Clemens, if it's not already clear, I have reached the limit of my knowledge at this point. We are both hoping that you can help solve this new bug. James, I can offer one suggestion: Try running JACK under strace, with playback-only at 64 frames/period. The strace output may indicate why JACK thinks an error occurred when in fact the USB transfers worked perfectly. > One thing is that another person affected by the same bug reports that > it may be hardware-specific: See: > > https://bugs.launchpad.net/ubuntu/+source/linux-lowlatency/+bug/1185563 > > Jori Neimi reports: "My laptop can handle jackd with a latency of 32 > samples on my Focusrite Scarlett 2i2 and 3.8.0-25 lowlatency kernel. > On my desktop jackd won't even start with a latency of less than 512 > samples using the same kernel and same USB audio device. No help from > the proposed 3.8.0-26, so I'll continue using 3.5.x kernels on my > desktop." > > Could this mean it is specific to some type of USB hardware on the motherboard?? Yes, with the existing drivers hardware differences can affect the result. But with Clemens's new patch applied, the hardware shouldn't matter. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
