Thread (8 messages) 8 messages, 4 authors, 2024-11-19

Re: [PATCH] cgroup/cpuset: Disable cpuset_cpumask_can_shrink() test if not load balancing

From: Juri Lelli <juri.lelli@redhat.com>
Date: 2024-11-19 06:03:11
Also in: lkml

On 18/11/24 22:28, Waiman Long wrote:
On 11/18/24 8:58 AM, Waiman Long wrote:
quoted
quoted
quoted
The failing test isn't an isolated partition. The actual test
failure is

Test TEST_MATRIX[62] failed result check!
C0-4:X2-4:S+ C1-4:X2-4:S+:P2 C2-4:X4:P1 . . X5 . . 0
A1:0-4,A2:1-4,A3:2-4
A1:P0,A2:P-2,A3:P-1

In this particular case, cgroup A3 has the following setting
before the X5
operation.

A1/A2/A3/cpuset.cpus: 2-4
A1/A2/A3/cpuset.cpus.exclusive: 4
A1/A2/A3/cpuset.cpus.effective: 4
A1/A2/A3/cpuset.cpus.exclusive.effective: 4
A1/A2/A3/cpuset.cpus.partition: root
Right, and is this problematic already?
We allow nested partition setup. So there can be a child partition
underneath a parent partition. So this is OK.
quoted
Then the test, I believe, does

# echo 5 >cgroup/A1/A2/cpuset.cpus.exclusive

and that goes through and makes the setup invalid - root domain reconf
and the following

# cat cgroup/A1/cpuset.cpus.partition
member
# cat cgroup/A1/A2/cpuset.cpus.partition
isolated invalid (Parent is not a partition root)
# cat cgroup/A1/A2/A3/cpuset.cpus.partition
root invalid (Parent is an invalid partition root)

Is this what shouldn't happen?
A3 should become invalid because none of the CPUs in
cpuset.cpus.exclusive can be granted. However A2 should remain a valid
partition. I will look further into that. Thank for spotting this
inconsistency.
Sorry, I misread the test. The X5 entry above refers to "echo 5 >
A1/A2/cpuset.cpus.exclusive" not to A3. This invalidates the A2 partition
which further invalidates the child A3 partition. So the result is correct.
OK, makes sense to me. But so, the test doesn't actually fail? Sorry,
guess I'm confused. :)
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