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Re: cyclictest
Posted: Tue Jan 15, 2019 1:48 pm
by merlyn
There's a new RT kernel 4.19.13-rt10-1-rt available and I tested it. The trend of gradual improvement is continuing.
- 4.19.13-rt10-1-rt #1 SMP PREEMPT RT.png (7.58 KiB) Viewed 1878 times
Again there's one rebellious core.
Re: cyclictest
Posted: Wed Jan 16, 2019 6:05 am
by merlyn
And a new low latency kernel came out: 4.20.1-arch1-1-ARCH. Comparing this plot to the previous one shows the difference between low latency (this) and real time (previous).
- 4.20.1-arch1-1-ARCH #1 SMP PREEMPT.png (8.74 KiB) Viewed 1872 times
Re: cyclictest
Posted: Wed Jan 16, 2019 12:14 pm
by gimmeapill
Interesting results. Even at 540 us worst case latency the stock kernel does quite ok'ish for audio.
Regarding those RT results with one core acting up: did you try to run the RT cyclictest with 3 cores?
I'm wondering if sacrificing one core wouldn't actually help.
It could be also a matter of RT priorities stepping on each other's toes. Do you have something like rtirq enabled?
Re: cyclictest
Posted: Wed Jan 16, 2019 5:40 pm
by merlyn
gimmeapill wrote:It could be also a matter of RT priorities stepping on each other's toes. Do you have something like rtirq enabled?
I do. rtirq behaves differently on Arch from on KXstudio. I have set RTIRQ_RESET_ALL=1 on both systems. On Arch I get this:
Code: Select all
★ /usr/bin/rtirq status
PID CLS RTPRIO NI PRI %CPU STAT COMMAND
353 FF 95 - 135 0.0 S irq/20-snd_ice1
61 FF 50 - 90 0.0 S irq/9-acpi
115 FF 50 - 90 0.0 S irq/8-rtc0
176 FF 50 - 90 0.0 S irq/17-ehci_hcd
188 FF 50 - 90 0.0 S irq/19-ehci_hcd
189 FF 50 - 90 0.0 S irq/14-pata_ati
190 FF 50 - 90 0.0 S irq/15-pata_ati
194 FF 50 - 90 0.0 S irq/24-ahci[000
206 FF 50 - 90 0.0 S irq/16-ohci_hcd
222 FF 50 - 90 0.0 S irq/16-ohci_hcd
223 FF 50 - 90 0.0 S irq/18-ohci_hcd
224 FF 50 - 90 0.0 S irq/18-ohci_hcd
225 FF 50 - 90 0.0 S irq/18-ohci_hcd
349 FF 50 - 90 0.0 S irq/19-snd_hda_
360 FF 50 - 90 0.0 S irq/18-radeon
383 FF 50 - 90 0.0 S irq/25-enp2s0
9 TS - 0 19 0.0 S ksoftirqd/0
27 TS - 0 19 0.0 S ksoftirqd/1
36 TS - 0 19 0.0 S ksoftirqd/2
45 TS - 0 19 0.0 S ksoftirqd/3
On KX no irqs except the soundcard are on scheduler FF.
I've found that I only get a rogue core when JACK is started. That would make sense as both JACK and cyclictest have a high priority.
Re: cyclictest
Posted: Thu Jan 17, 2019 2:35 pm
by merlyn
I ran
mklatencyplot.bash again without JACK, and got this:
- 4.19.13-rt10-1-rt #1 SMP PREEMPT RT No JACK.png (7.28 KiB) Viewed 1853 times
That's a very low maximum latency. One core having a higher maximum latency than the others was due to JACK. I don't think the previous plots show a problem, because the maximum latency is still under the recommended 100us, even with hackbench running and two high priority threads (JACK and cyclictest) competing for a core. In normal audio use JACK wouldn't have to compete with other high priority threads like those used by cyclictest.
Re: cyclictest
Posted: Wed Mar 06, 2019 2:04 am
by pawan4749
# 8. Execute plot command
gnuplot -persist <plotcmd
I'm running the cyclictest but getting error as:
gnuplot: command not found
Any help please to overcome this.
Re: cyclictest
Posted: Wed Mar 06, 2019 2:13 pm
by merlyn
Hi pawan4749. You need to install gnuplot. On ubuntu this would be
Re: cyclictest
Posted: Thu Mar 07, 2019 7:39 am
by pawan4749
Hi Merlyn,
Thanks for your suggestion.
Im running cyclictest on rt-kernel image of 4.14.
sudo apt-get install gnuplot command is not working.
Results:
apt-get: Command not found
Re: cyclictest
Posted: Thu Mar 07, 2019 1:13 pm
by merlyn
What distro are you using?
Re: cyclictest
Posted: Sat Mar 09, 2019 7:36 am
by pawan4749
I'm using poky (Yocto)
Re: cyclictest
Posted: Sun Mar 10, 2019 2:56 pm
by merlyn
OK, that's a distro aimed at embedded systems? I'm not familiar with it. You managed to install rt-tests. Or did that come with the distro?
However you install software on your distro, use that method to install gnuplot. You may have to download the gnuplot source and compile it.
Re: cyclictest
Posted: Mon Oct 07, 2019 1:15 pm
by pawan4749
Hi
I have created python script for the cyclictest command "cyclictest -l100000000 -m -Sp90 -i200 -h100000000" and running on target through remotely (using ssh). But, it is taking abnormal time around 13 hrs, 15 hrs.
can any one please suggest what can be the reason(do executing script through ssh may have any effect).
Re: cyclictest
Posted: Wed Oct 09, 2019 2:17 pm
by merlyn
I'm using :
Code: Select all
cyclictest -l100000000 -m -Sp90 -i200 -h400 -q
Why are you using a large value for
-h?
Re: cyclictest
Posted: Thu Oct 10, 2019 5:57 pm
by pawan4749
As I'm using -l loops as 100 million , so for histograms also using100 million
Re: cyclictest
Posted: Thu Oct 10, 2019 7:04 pm
by merlyn
That could be the problem. From the
cyclictest manpage :
Code: Select all
-h, --histogram=US
Dump latency histogram to stdout after the run. US is the max
latency time to be be tracked in microseconds. This option runs
all threads at the same priority.
100000000 microseconds is 100 seconds.