Re: [PATCH] Cpuset: rcu optimization of page alloc hook

[Andi Kleen]

> But, boy oh boy, that synchronize_rcu() call sure takes it time.
> 
> My cpuset torture test was creating, destroying and abusing about 2600
> cpusets/sec before this change, and now it does about 144 cpusets/sec.
> 
> That cost 95% of the performance.  This only hits on the cost of
> attaching a task to a different cpuset (by writing its <pid> to
> some other cpuset 'tasks' file.)

That is why call_rcu.et.al. is a better interface if you want performance.
It runs the freeing batched in the background.

-Andi
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