Re: [Lse-tech] [PATCH] cpusets - big numa cpu and memory placement

[Paul Jackson]

Martin wrote:
> Then when I fork off exclusive subset for CPUs 1&2, I have to push A & B
> into it.

Tasks A & B must _not_ be considered members of that exclusive cpuset,
even though it seems that A & B must be attended to by the sched_domain
and memory_domain associated with that cpuset.

The workload managers expect to be able to list the tasks in a cpuset,
so it can hibernate, migrate, kill-off, or wait for the finish of these
tasks.  I've been through this bug before - it was one that cost Hawkes
a long week to debug - I was moving the per-cpu migration threads off
their home CPU because I didn't have a clear way to distinguish tasks
genuinely in a cpuset, from tasks that just happened to be indigenous to
some of the same CPUs.  My essential motivation for adapting a cpuset
implementation that has a task struct pointer to a shared cpuset struct
was to track exactly this relation - which tasks are in which cpuset.

No ... tasks A & B are not allowed in that new exclusive cpuset.

-- 
                          I won't rest till it's the best ...
                          Programmer, Linux Scalability
                          Paul Jackson <pj@xxxxxxx> 1.650.933.1373
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