5 Mar
2020
5 Mar
'20
6:49 p.m.
Hi list,
https://www.rncbc.org/drupal/user/register did not load, so I hope it's
okay to ask here.
Performance of my audio system somehow degraded so I tried to find the
culprit.
/etc/default/rtirq looks liks this:
# IRQ thread service names
# (space separated list, from higher to lower priority).
RTIRQ_NAME_LIST="snd usb i8042"
# Highest priority.
RTIRQ_PRIO_HIGH=90
# Priority decrease step.
RTIRQ_PRIO_DECR=5
# Lowest priority.
RTIRQ_PRIO_LOW=51
# Whether to reset all IRQ threads to SCHED_OTHER.
RTIRQ_RESET_ALL=0
# On kernel configurations that support it,
# which services should be NOT threaded
# (space separated list).
RTIRQ_NON_THREADED="rtc snd"
but even so,
$ /etc/init.d/rtirq status
PID CLS RTPRIO NI PRI %CPU STAT COMMAND
595 FF 50 - 90 0.0 S irq/34-mei_me
634 FF 50 - 90 0.0 S irq/36-iwlwifi
730 FF 50 - 90 0.0 S irq/39-rmi4_smb
1619 FF 50 - 90 2.9 S irq/35-nvidia
10 TS - 0 19 0.0 S ksoftirqd/0
18 TS - 0 19 0.0 S ksoftirqd/1
24 TS - 0 19 0.0 S ksoftirqd/2
30 TS - 0 19 0.0 S ksoftirqd/3
36 TS - 0 19 0.0 S ksoftirqd/4
42 TS - 0 19 0.0 S ksoftirqd/5
48 TS - 0 19 0.0 S ksoftirqd/6
54 TS - 0 19 0.0 S ksoftirqd/7
I was expecting to see snd and usb on this list or am I mistaken?
m.
5 Mar
5 Mar
7:59 p.m.
On 05.03.20 18:49, Max wrote:
I was expecting to see snd and usb on this list or am
I mistaken?
ah, after changing
GRUB_CMDLINE_LINUX=""
to
GRUB_CMDLINE_LINUX="threadirqs"
in /etc/default/grub
and then doing
sudo update-grub
it looks differently:
PID CLS RTPRIO NI PRI %CPU STAT COMMAND
671 FF 90 - 130 0.0 S irq/37-snd_hda_
673 FF 90 - 130 0.0 S irq/38-snd_hda_
185 FF 85 - 125 0.0 S irq/16-ehci_hcd
187 FF 85 - 125 0.4 S irq/29-xhci_hcd
186 FF 84 - 124 0.0 S irq/23-ehci_hcd
189 FF 80 - 120 0.0 S irq/1-i8042
188 FF 79 - 119 0.0 S irq/12-i8042
164 FF 50 - 90 0.0 S irq/9-acpi
190 FF 50 - 90 0.0 S irq/8-rtc0
283 FF 50 - 90 0.0 S irq/18-i801_smb
289 FF 50 - 90 0.0 S irq/30-rtsx_pci
293 FF 50 - 90 0.5 S irq/31-ahci[000
318 FF 50 - 90 0.0 S irq/33-i915
613 FF 50 - 90 0.0 S irq/35-mei_me
649 FF 50 - 90 0.0 S irq/36-iwlwifi
777 FF 50 - 90 0.0 S irq/39-rmi4_smb
1533 FF 50 - 90 0.0 S irq/32-enp4s0
1601 FF 50 - 90 0.6 S irq/34-nvidia
650 FF 49 - 89 0.0 S irq/36-s-iwlwif
1602 FF 49 - 89 2.3 S irq/34-s-nvidia
so maybe this got lost somehow.
8 Mar
8 Mar
10:55 a.m.
Is there a way to verify if the kernel was loaded with the threadirqs
option, so this test could be added to realtimeconfigquickscan?
12:54 p.m.
On 8/3/20 8:55 pm, Max wrote:
Is there a way to verify if the kernel was loaded with
the threadirqs
option, so this test could be added to realtimeconfigquickscan?
Interesting question and it came up using a quick search of you question
in the first few results, in the Mixxx wiki -
https://www.mixxx.org/wiki/doku.php/adjusting_audio_latency
grep threadirqs /proc/cmdline
I didn't test it as I'm not in my audio system at present.
There is also some other worthwhile info in that wiki page.
9 Mar
9 Mar
12:19 a.m.
On Sun, March 8, 2020 6:53 am, Roger wrote:
On 8/3/20 8:55 pm, Max wrote:
With the caveat that you will also need to check whether the kernel is
running the full RT patch, in which case IRQ handling is always threaded,
so the threadirqs command line option is not needed. Also note that even
with the threadirqs command line, I do not think threaded IRQ handling is
implemented if the PREEMPT option is not selected when the kernel is
compiled. That was the case in the past, I have not verified it is still
the case with the very latest, although if you are looking for low latency
you will probably want to verify that the kernel is configured with at
least PREEMPT if not using the full PREEMPT-RT patches.
--
Chris Caudle
Is there a way to verify if the kernel was loaded
with the threadirqs
option, so this test could be added to realtimeconfigquickscan?
Interesting question and it came up using a quick search of you question
in the first few results, in the Mixxx wiki -
https://www.mixxx.org/wiki/doku.php/adjusting_audio_latency
grep threadirqs /proc/cmdline
12:10 p.m.
On 09.03.20 00:19, Chris Caudle wrote:
On Sun, March 8, 2020 6:53 am, Roger wrote:
I had the feeling this is quite complex to put into a script that checks
for all these cases and gives a recommendation.
https://github.com/raboof/realtimeconfigquickscan/issues/31
If you know how to query for those different options please share.
On 8/3/20 8:55 pm, Max wrote:
With the caveat that you will also need to check whether the kernel is
running the full RT patch, in which case IRQ handling is always threaded,
so the threadirqs command line option is not needed. Also note that even
with the threadirqs command line, I do not think threaded IRQ handling is
implemented if the PREEMPT option is not selected when the kernel is
compiled. That was the case in the past, I have not verified it is still
the case with the very latest, although if you are looking for low latency
you will probably want to verify that the kernel is configured with at
least PREEMPT if not using the full PREEMPT-RT patches.
Is there a way to verify if the kernel was loaded
with the threadirqs
option, so this test could be added to realtimeconfigquickscan?
Interesting question and it came up using a quick search of you question
in the first few results, in the Mixxx wiki -
https://www.mixxx.org/wiki/doku.php/adjusting_audio_latency
grep threadirqs /proc/cmdline
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Roger