Re: cpusets not cpu hotplug aware

From: Paul Jackson
Date: Mon Aug 21 2006 - 13:41:30 EST

Anton wrote:
> We have a bug report where sched_setaffinity fails for cpus that are
> hotplug added after boot. Nathan found this suspicious piece of code:
> void __init cpuset_init_smp(void)
> {
> top_cpuset.cpus_allowed = cpu_online_map;
> top_cpuset.mems_allowed = node_online_map;
> }
> Any reason we statically set the top level cpuset to the boot time cpu
> online map?

Your query confuses me, about 4 different ways ...

1) What does sched_setaffinity have to do with this part of cpusets?
2) What did you mean by "statically assigned"? At boot, whatever cpus
and memory nodes are online are copied to the top_cpuset's settings.
As Simon suggests, it would be up to the hotplug/hotunplug folks to
update these top_cpuset settings, as cpus and nodes come and go.
3) I don't understand what you thought was suspicious here.
4) I don't understand what you expected to see instead here.

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