On 8/27/24 04:01, Michal Koutný wrote:
Hi.
On Tue, Aug 20, 2024 at 03:55:35PM GMT, Waiman Long <longman@xxxxxxxxxx> wrote:
The prstate_housekeeping_conflict() function does check the
HK_TYPE_DOMAIN housekeeping cpumask to make sure that CPUs outside of it
can only be used in isolated partition.
Given the fact that we are going to make housekeeping cpumasks
dynamic, the current check may not be right anymore. Save the boot
time HK_TYPE_DOMAIN cpumask and check against it instead of the
upcoming dynamic HK_TYPE_DOMAIN housekeeping cpumask.
Why is (will be) checking against the stored HK_TYPE_DOMAIN mask correct
when this mask becomes dynamic?
In term of isolated CPUs, there are 2 categories - static and dynamic.
Statically isolated CPUs are those that are designed as isolated at boot
time by "isolcpus". Other isolated CPUs created by the cpuset isolated
partitions are considered dynamic in the sense that its state can change
at run time. The degree of CPU isolation of dynamically isolated CPUs
isn't as good as that of the statically isolated ones. So I want to
handle them separately which is what the prstate_housekeeping_conflict()
is intended to do.
As it is my intention to make the housekeeping cpumasks dynamic, I need
to keep a copy of the statically isolated CPUs and check against them.
There is no point to check dynamically isolated CPUs as the test may
produce a false positive result.
In the future when dynamic CPU isolation is as almost as good as the
static ones, we can get rid of this distinction and treat all of them as
dynamic.
Cheers,
Longman
