[arch-proaudio] cyclictest

[Ralf Mardorf]

On Sat, 23 Dec 2017 02:37:18 +0100, Ralf Mardorf wrote:
>On Fri, 22 Dec 2017 20:54:47 +0100, LX wrote:
>>On Fri, 22 Dec 2017 06:33:11 +0100, Ralf Mardorf wrote:  
>
>>Intel(R) Core(TM) i5-3317U CPU @ 1.70GHz
>>4.14.6-rt7-1-rt
>>[root at pill-mobile4 gimmeapill]# cyclictest -S -m -p98
>># /dev/cpu_dma_latency set to 0us
>>policy: fifo: loadavg: 0.10 0.06 0.02 1/161 521
>>Max:      15  
>
>>>Intel(R) Celeron(R) CPU G1840 @ 2.80GHz
>>>4.14.6-rt7-1-rt
>>>cyclictest -S -m -p98
>>>WARN: open /dev/cpu_dma_latency: Permission denied
>>>policy: fifo: loadavg: 0.13 0.09 0.02 1/208 4690          
>>>
>>>T: 0 ( 1245) P:98 I:1000 C:35539474 Min:      1 Act:   31 Avg:   27
>>>Max:      83  
>
>Hi,
>
>does the CPU make such a big difference? If so, I'll order another CPU
>today. Or is it the combination of CPU and mobo that does cause such a
>big difference?
>
>Is there a reason to run cyclictest as root? We do audio work as an
>user without root privileges.
>
>This short run already seems to answer my questions:
>
>[root at archlinux rocketmouse]# uname -rm
>4.14.6-rt7-1-rt x86_64
>[root at archlinux rocketmouse]# cyclictest -S -m -p98
># /dev/cpu_dma_latency set to 0us
>policy: fifo: loadavg: 0.00 0.02 0.00 1/254 10107          
>
>T: 0 (10106) P:98 I:1000 C:   8583 Min:      1 Act:    1 Avg:    1
>Max:       6 T: 1 (10107) P:98 I:1500 C:   5720 Min:      1 Act:    1
>Avg:    1 Max:       6 ^C[root at archlinux rocketmouse]#
>
>However, regarding my questions the manpage of cyclictest isn't
>helpful.

PS: What does it all mean? A cheap Intel(R) Celeron(R) CPU G1840 @
2.80GHz has got less latency, than a much more expensive Intel(R)
Core(TM) i5-3317U CPU @ 1.70GHz? How does it affect audio work? What is
the relevance of cyclictest? Is the result somehow related to audio
latency and/or MIDI jitter?