Re: [PATCH tip/core/rcu 0/2] rcu: v2: more review feedback

From: Josh Triplett
Date: Mon Sep 28 2009 - 12:10:07 EST


On Mon, Sep 28, 2009 at 07:45:51AM -0700, Paul E. McKenney wrote:
> This patchset applies the last of the review comments:
>
> o Whitespace fixes, updated comments, and code movement.
>
> o Improve an existing abstraction and introduce two additional
> abstractions for traversing the rcu_node tree.
>
> Change since v1 (http://lkml.org/lkml/2009/9/27/17):
>
> o Update second patch's changelog
>
> Issues remaining:
>
> o I can force hangs given sufficient rcutorture testing in
> conjunction with random CPU-hotplug operations. I am working
> on a simpler interface between RCU and CPU hotplug that I
> believe will clear this up.
>
> o TREE_PREEMPT_RCU currently uses the TREE_RCU variant of
> synchronize_rcu_expedited, which is wrong. I am working on
> an expedited variant for TREE_PREEMPT_RCU, but will fall
> back on synchronize_rcu() for the short term if it gives me
> much trouble.
>
> o The IPI hyperactivity from call_rcu() noted by Nick Piggin.
> I believe I have identified a clean design for a fix for this.
>
> o Make RCU less dependent on IPIs for forcing grace periods
> (but this might be best deferred to 2.6.33).
>
> o RCU priority boosting (2.6.33!).
>
> o TINY_PREEMPT_RCU (2.6.33!).
>
> o Squeeze another 400 bytes or so out of TINY_RCU (2.6.33!).
>
>
> b/include/linux/rcupdate.h | 14 +++++------
> b/kernel/rcutree.c | 11 ++++-----
> b/kernel/rcutree.h | 12 ++++++++++
> b/kernel/rcutree_plugin.h | 5 ----
> kernel/rcutree.c | 53 +++++++++++++++++++++++----------------------
> 5 files changed, 52 insertions(+), 43 deletions(-)

For both patches:
Acked-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
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