26 Mar
2018
26 Mar
'18
2:45 a.m.
Hi Chris,
Not sure how much this helps, but I have been running the audioinjector octocard (6 in/8
out) on a RPi 3, with stable streaming down to 8 frames per buffer, with a distribution
called RealtimePi (https://github.com/guysoft/RealtimePi) Unfortunately I don't know
the specific kernel details of it.
My exact setup can be found here:
http://forum.audioinjector.net/viewtopic.php?f=5&t=2727&start=30#p5…
Problem of course is that the lower the buffer size, the higher the CPU utilization. With
64 frames per buffer, the latency/CPU tradeoff is acceptable (I think with 8 frame per
buffer, I had nearly 100% CPU just shoveling audio from input to output, with 64 it's
~10%).
Regards
/Robert
-----Original Message-----
From: Jack-Devel <jack-devel-bounces(a)lists.jackaudio.org> On Behalf Of
Christopher Obbard
Sent: den 25 mars 2018 12:32
To: jack-devel(a)lists.jackaudio.org
Subject: [Jack-Devel] Fwd: connecting to JACKD2 with low buffer sizes
Hi Guys,
Running jack with a small buffer (-p64 -n2), and connecting with any
client causes issues.
With higher buffer sizes, all is OK.
This is on an ARM embedded system, with a single core 1MHz processor.
I've set the cpu governor to performance.
I have a custom compiled 4.14 kernel with omap2plus_defconfig with the
following config settings:
CONFIG_PREEMPT_VOLUNTARY=y
HZ_100=y
CONFIG_NO_HZ_IDLE=y
$ jackd -R -P95 -dalsa -dhw:0 -r48000 -p64 -n2
JackPosixProcessSync::LockedTimedWait error usec
= 5000000 err =
Connection timed out
Driver is not running
Cannot create new client
CheckSize error size = 32 Size() = 12
CheckRead error
CheckSize error size = -1 Size() = 4
CheckRead error
CheckSize error size = 0 Size() = 12
CheckRead error
Also, with higher buffer sizes sometimes I get xruns. After enabling
alsa debugging, the error is:
ALSA: PCM: [Q] Lost interrupts?: (stream=0,
delta=221,
new_hw_ptr=181343, old_hw_ptr=181122)
Loosing the FIFO interrupts doesn't seem like a great thing.........
I _think_ the issue is to do with the kernel scheduling, but this why
I ask the experts :-).
Can anyone suggest any kernel settings that will improve my situation?
Many thanks,
Chris
_______________________________________________
Jack-Devel mailing list
Jack-Devel(a)lists.jackaudio.org
http://lists.jackaudio.org/listinfo.cgi/jack-devel-jackaudio.org