Re: cpusets not cpu hotplug aware

From: Paul Jackson
Date: Wed Aug 23 2006 - 15:06:30 EST

Anton wrote:
> We have a userspace visible change to the sched
> affinity API when the cpusets option is enabled.

Yup - on cpuset kernels, sched_setaffinity is constrained to CPUs in a
tasks cpuset. Also mbind and set_mempolicy are constrained to nodes in
the tasks cpuset.

This is a long standing, intentional part of the cpuset design.

Using udev isn't papering over it. It's reflecting the reasonable
preference and expectation on systems using hotplug/unplug that
the default cpuset dynamically reflect the current online maps,
not the static maps as they were at boot. And using udev is using
just the sort of mechanism one might expect to be used to adjust
the system when devices go on or off line.

I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@xxxxxxx> 1.925.600.0401
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