CFS process priority tests

Setup

OS: ubuntu 19.10

Machine: qemu-kvm

Make sure to disable the autogroup feature, which is enabled by default. The autogroup automatically creates a CPU control group for each new session, and the group weights overrides pricess priorities. So with autogrouping enabled, changing process priorities may not have any effect.

Run the following command to disable autogroup:

root@emu:~# echo 0 > /proc/sys/kernel/sched_autogroup_enabled

The test script is at genload.py

Test 1

In the 1st terminal:

root@emu:~# python3 genload.py 
...
[02:03:07] count 1,892,493 pcpu 73(73) exec_time 491(491)
... (renice 2nd process)
[02:03:08] count 2,165,950 pcpu 72(72) exec_time 538(538)
[02:03:09] count 2,071,702 pcpu 72(72) exec_time 548(548)
[02:03:10] count 2,060,509 pcpu 72(72) exec_time 547(547)

In the 2nd terminal:

root@emu:~# python3 genload.py 
...
[02:03:07] count 1,921,506 pcpu 49(49) exec_time 490(490)
... (renice +1)
[02:03:08] count 1,832,973 pcpu 49(49) exec_time 446(446)
[02:03:09] count 1,676,413 pcpu 49(49) exec_time 439(439)
[02:03:10] count 1,682,007 pcpu 48(48) exec_time 442(442)

Test 2

In the 1st terminal:

root@emu:~# python3 genload.py 
...
[02:34:18] count 951,643 pcpu 73(73) exec_time 248(248)
[02:34:19] count 1,006,798 pcpu 71(71) exec_time 237(237)
(renice +1)
[02:34:20] count 807,376 pcpu 70(70) exec_time 203(203)
[02:34:21] count 869,612 pcpu 68(68) exec_time 206(206)

In the other 3 terminals:

root@emu:~# python3 genload.py
...
[02:34:18] count 974,679 pcpu 22(22) exec_time 247(247)
[02:34:19] count 943,301 pcpu 23(23) exec_time 242(242)
(renice 1st process)
[02:34:20] count 1,016,265 pcpu 23(23) exec_time 259(259)
[02:34:21] count 1,025,985 pcpu 23(23) exec_time 258(258)