Messages in this thread | | | Date | Tue, 20 Sep 2022 12:18:38 +0200 | Subject | Re: [PATCH v4 4/8] sched/core: Add permission checks for setting the latency_nice value | From | Tim Janik <> |
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Hi.
On 19.09.22 14:41, Vincent Guittot wrote: > Hi, > > Thanks you for describing in detail your use case.
> Ok, Your explanation makes sense to me especially because we want to > ensure to not provide more cpu time with this latency prio. I'm > curious to see the feedback from others about the reason we want > CAP_SYS_NICE other than following nice priority. > > Side question, Have you tried this patchset (minus this patch) with > your use case ?
I have now tested a modified version of the ALSA Test_latency.c program that acquires latency nice as non-root: https://gist.github.com/tim-janik/88f9df5456b879ecc59da93dc6ce6be1
With a busy but not overloaded CPU, the short time latency tests are often better, measured with: ./lnice-latency -p -s 1
But the results aren't very reliable with this test. I.e. requesting a latency nice value of -20 reduces the chance for underruns somewhat but doesn't eliminate them (and lnice-latency.c gives up on the first XRUN in the given time period). It might be better to instead count the XRUN occurances over a given time pertiod.
-- Anklang Free Software DAW https://anklang.testbit.eu/
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