[PATCH 07/41] cpuset: Set up interface for nohz flag
cl at linux.com
Tue May 8 15:57:21 UTC 2012
On Tue, 8 May 2012, Peter Zijlstra wrote:
> > For some reason this seems to work here. What is broken with isolcpus?
> It mostly still works I think, but iirc there were a few places that
> ignored the cpuisol mask.
Yes there is still superfluous stuff going on on isolated processors.
> But really the moment we get proper means of flushing cpu state
> (currently achievable by unplug-replug) isolcpu gets depricated and
> eventually removed.
Not sure what that means and how that is relevant. Scheduler?
> cpusets can do what isolcpu can and more (provided this flush thing).
cpusets is a pretty heavy handed thing and causes inefficiencies in the
allocators if compiled into the kernel because checks will have to be done
in hot allocation paths.
> > > Furthermore there is no other partitioning scheme, cpusets is it.
> > One can partition the system anyway one wants by setting cpu affinities
> > and memory policies etc. No need for cpusets/cgroups.
> Not so, the load-balancer will still try to move the tasks and
> subsequently fail. Partitioning means it won't even try to move tasks
> across the partition boundary.
Ok so the scheduler is inefficient on this. Maybe that can be improved?
Setting affinities should not cause overhead in the scheduler.
> By proper partitioning you can split load balance domains (or completely
> disable the load-balancer by giving it a single cpu domain).
I thought that was the point of isolcpus?
More information about the linaro-sched-sig