[PlanetCCRMA] XRUNS and more
Fernando Lopez-Lezcano
nando at ccrma.Stanford.EDU
Fri May 13 08:43:36 PDT 2016
On 05/13/2016 05:15 AM, Etienne Rouge wrote:
> Hello,
Hi Etienne,
> I've recently switched back to CCRMA and I'm rather happy with it.
>
> However I still have xruns when I really shouldn't (powerfull computer
> and reasonnable amount of tracks/effects).
>
> I've set up PAM… added "rtc firewire_ohci" to the irq file. Honestly, I
> don't quite understand the few tuts I find online and the fact they are
> not fedora-oriented don't help.
>
> Is there a crucial step I've missed ? A tutorial I can follow ?
Could you tell us what hardware is this? What software are you running?
I presume you are running rtirq and you have access to SCHED_FIFO rt
scheduling in your account.
I have found that for critical low latency work using recent hardware I
need to disable hyperthreading (the fake cores on Intel processors that
can't do much) and also set the intel_pstate driver to try to use all
cores at high speed. Also disable thermald if you are using it (it could
also be throttling the processors). Maybe this would help?
I have this in a script I run when needed (this is on a four core Intel
laptop with HT):
# get all processors to run fast all the time...
echo "100" > /sys/devices/system/cpu/intel_pstate/min_perf_pct
# turn off hyperthreading which only makes things worse most of the time
# we do this by turning off cpus that have the same "proc id"
echo 0 > /sys/devices/system/cpu/cpu1/online
echo 0 > /sys/devices/system/cpu/cpu3/online
echo 0 > /sys/devices/system/cpu/cpu5/online
echo 0 > /sys/devices/system/cpu/cpu7/online
Best luck! And let us know how it works out...
-- Fernando
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