Interesting, thanks Rik. I assumed that couldn't be correct, since it would result in lower priority tasks receiving a slice less than the sysctl_sched_min_granularity - which I assumed CFS explicitly aims to prevent. Thanks for taking a look. On Fri, Apr 3, 2020 at 1:51 AM Valdis Klētnieks <valdis.kletnieks@vt.edu> wrote:
On Thu, 02 Apr 2020 22:10:11 -0400, Evan T Mesterhazy said:
I ran a test by starting five busy processes with a nice level of -10. Next, I launched ~40 busy processes with a nice level of 0 (all procs were set to use the same CPU). I expected CFS to expand the period and assign each process a slice equal to the min granularity. However, the 5 processes with nice = -10 still used considerably more CPU than the other processes.
Well, it's *expected* that if you set nice = -10 they'll get more CPU.
Do you have any evidence that CFS *didn't* give the nice==0 processes a min_granularity slide once in a while?
-- Evan Mesterhazy etm2131@columbia.edu