hello everyone!
this is not exactly about audio-development, but the DRI+jack thread encouraged me to ask a few questions about optimizing my setup:
i'm using a rme hdsp (cardbus) + multiface with my 1ghz pIII laptop for quite a while now, and i'm happy with it.
i would like to use the setup for live-processing but the lowest jackd framesize i can safely use is 2048. the main issue here seems to be the nvidia graphics card.
since i switched from kernel 2.4.2x+lowlat+capabilities to 2.6.1 the cpu-load seems to be noticable higher for ardour, but the latency-issue did not change.
so my questions are:
*) is anybody successfully using hdsp-cardbus with really low latencies ?
I'm using the same setup as you (hdsp+cardbus+1GHz PIII+nvidia binary drivers+2.6.1) and can use low latency without any problem. I use jack with the -R flag as a user thanks to Jack O'Quin's excellent 'realtime' module. Before that I used 2.4.x-ck and was also quite happy with it. The only latency killer apps I could identify at the time were applications accessing ACPI features (notably gnome's batstat applet). The ACPI situation has been much improved for me in the 2.6.x kernels (thanks to the CONFIG_ACPI_RELAXED_AML option - I have a toshiba laptop with a buggy BIOS)
*) how important is the firmware version - which firmware version should i use for my hdsp card?
Firmware version shouldn't change anything.
*) did anyone else notice increasing cpu load with audio-apps + kernel 2.6.x ?
I didn't.
*) any hints about configuring X11 for linux-audio (besides from DRI questions ;-) ?
You could try the open source nv driver that's shipped with X. You'll loose 3rd acceleration, though.
let me know if you think i'm on the wrong list should better alsa-dev.
I don't think for now that this is a driver issue, but can be wrong.
What version of alsa are you using ?
What happens when you run jack with period size < 2048 ? I guess jack reports xruns, but do they seem to appear regularly or randomly ? In your description you seem to imply that you do not have this latency problem when running without X, is it the case ? How low can you get running jack in text mode ? Generally speaking, can you find any relation between the xruns and system activity (disk access, incoming midi stream, GUI interaction, etc...) ?
Thomas
