CPU usage limitation (number of cores)

From: Mahmood Naderan <mahmood.nt@gmail.com>
To: linux-kernel@vger.kernel.org
Subject: CPU usage limitation (number of cores)
Date: Tue, 22 Mar 2016 13:09:42 +0430	[thread overview]
Message-ID: <CADa2P2US62K4xWSiEbM=DQ-OC1xQB15D20w3jE7hbEBEVZ4M6w@mail.gmail.com> (raw)

Hi,
There is a question about CPU usage limitation and I found no place
for my question other than here.

There are 32 cores in a system (2 cpus each 16 cores) and I want to
limit a user to use only 4 cores (100% usage for that 4 cores). There
are two kernel parameter for that according to the manuals:
cpu.cfs_quota_us and cpu.cfs_period_us

An example on the kernel.org documents says:

With 500ms period and 1000ms quota, the group
can get 2 CPUs worth of runtime every 500ms.
# echo 1000000 > cpu.cfs_quota_us /* quota = 1000ms */
# echo 500000 > cpu.cfs_period_us /* period = 500ms */

I want to know how those ms are determined? In my case, I think the
quota is 32000000 and the period is 4000000. Am I right?
But it doesn't work! and I get an error when I want to start cgroup service

Failed to parse /etc/cgconfig.conf or /etc/cgconfig.d
[FAILED]Starting cgconfig service: /sbin/cgconfigparser; error loading
/etc/cgconfig.conf: Failed to remove a non-empty group

Reference:
https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt

Regards,
Mahmood