Re: [PATCH tip/core/rcu 07/86] rcu: Force per-rcu_node kthreads offof the outgoing CPU

[Josh Triplett]

On Sun, May 01, 2011 at 06:20:47AM -0700, Paul E. McKenney wrote:
> From: Paul E. McKenney <paul.mckenney@xxxxxxxxxx>
> 
> The scheduler has had some heartburn in the past when too many real-time
> kthreads were affinitied to the outgoing CPU.  So, this commit lightens
> the load by forcing the per-rcu_node and the boost kthreads off of the
> outgoing CPU.  Note that RCU's per-CPU kthread remains on the outgoing
> CPU until the bitter end, as it must in order to preserve correctness.
> 
> Also avoid disabling hardirqs across calls to set_cpus_allowed_ptr(),
> given that this function can block.

This seems like two separate changes in one patch.  The change to
kernel/rcutree_plugin.h seems entirely separable from the change to
kernel/rcutree.c here.

> Signed-off-by: Paul E. McKenney <paul.mckenney@xxxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

Heh, amusingly this actually seems meaningful, if you intend it as a
"role" approval.

- Josh Triplett
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