Page 2 of 2
Posted: Tue Jan 15, 2019 1:48 pm
There's a new RT kernel 4.19.13-rt10-1-rt available and I tested it. The trend of gradual improvement is continuing.
Again there's one rebellious core.
Posted: Wed Jan 16, 2019 6:05 am
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).
Posted: Wed Jan 16, 2019 12:14 pm
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?
Posted: Wed Jan 16, 2019 5:40 pm
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.
Posted: Thu Jan 17, 2019 2:35 pm
I ran mklatencyplot.bash again without JACK, and got this:
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.
Posted: Wed Mar 06, 2019 2:04 am
# 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.
Posted: Wed Mar 06, 2019 2:13 pm
Hi pawan4749. You need to install gnuplot. On ubuntu this would be
Posted: Thu Mar 07, 2019 7:39 am
Thanks for your suggestion.
Im running cyclictest on rt-kernel image of 4.14.
sudo apt-get install gnuplot command is not working.
apt-get: Command not found
Posted: Thu Mar 07, 2019 1:13 pm
What distro are you using?
Posted: Sat Mar 09, 2019 7:36 am
I'm using poky (Yocto)
Posted: Sun Mar 10, 2019 2:56 pm
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.
Posted: Mon Oct 07, 2019 1:15 pm
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).
Posted: Wed Oct 09, 2019 2:17 pm
I'm using :
Code: Select all
cyclictest -l100000000 -m -Sp90 -i200 -h400 -q
Why are you using a large value for -h
Posted: Thu Oct 10, 2019 5:57 pm
As I'm using -l loops as 100 million , so for histograms also using100 million
Posted: Thu Oct 10, 2019 7:04 pm
That could be the problem. From the cyclictest
Code: Select all
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.