On 08/25/2014 07:02 AM, Harry van Haaren wrote:
On Mon, Aug 25, 2014 at 2:55 PM, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
You tried both these as root? Even 'sudo' may not work..
Yes, the original output was all as root (not sudo, genuine root).
I haven't seen the rt code since sometime, what tag should I look at ?
I'm running 3.14.12-rt9-1-rt (as packaged for Arch here:
https://aur.archlinux.org/packages/linux-rt )
Hi Harry,
Check to see if you see something in /sys/devices/system/cpu/intel_pstate/
If so then the intel pstate driver is what is controlling cpu speed for
you (that changed since 3.9 or so). You can set min_perf_pct to "100" to
set your minimum cpu speed to the maximum possible. Even then you will
see some variation but in my usage case jackd is again usable after this
change[*].
See:
https://wiki.archlinux.org/index.php/CPU_frequency_scaling
-- Fernando
[*] I think the intel pstate drive is not yet aware of what the
scheduler does with tasks (or visceversa). In the case of jackd I think
that the scheduler can move a task to a processor that is throttled down
and the change in speed after detecting high load does not happen fast
enough. Jackd runs out of cpu cycles and you get an xrun. By the next
jackd cycle the cpu is running up to speed and everything is fine but
the task might be moved again to a different core. Just speculation on
my part.
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