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

From: Paul E. McKenney
Date: Mon Sep 28 2009 - 10:46:03 EST


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(-)
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