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Preview of RCU patches for 2.6.40

From:  "Paul E. McKenney" <>
Subject:  [PATCH tip/core/rcu 0/6] Preview of RCU patches for 2.6.40
Date:  Sun, 1 May 2011 06:21:42 -0700
Message-ID:  <>
Archive-link:  Article


This patchset introduces RCU_TREE priority boosting, a new "fire and
forget" kfree_rcu() API, numerous uses of kfree_rcu(), plus a number
of other fixes and improvements.  The patches are as follows:

1.	Remove conditional compilation for RCU CPU stall warnings, which
	are now controlled only by the boot command line and sysfs.

2.	Reworks RCU dyntick-idle interface to better tolerate theoretical
	races introduced by expedited grace periods.

3-9.	Introduce RCU priority boosting for TREE_RCU.

10-19.	Upgrace TREE_RCU tracing to accommodate RCU priority boosting
	and update documentation.

20-23.	Make DEBUG_OBJECTS_RCU_HEAD work from !PREEMPT (thanks to
	Mathieu Desnoyers).

24.	Switch to this_cpu() primitives (thanks to Christoph Lameter).

25-27.	Apply TREE_RCU priority-boosting lessons learned to TINY_RCU.

28.	Avoid spurious diagnostics by moving from rcu_read_unlock() to
	__rcu_read_unlock() in exit() patch (thanks to Lai Jiangshan).

29.	Settle on "preemptible" spelling vs. "preemptable".

30.	Introduce kfree_rcu() (thanks to Lai Jiangshan).

31.	"Nice" down processes in rcu_yield(), which is called by RCU's
	per-CPU kthreads to avoid monopolizing the CPU.

32.	Improve latency by having call_rcu() avoid diving into the
	RCU core code when called with irqs disabled.

33.	Further reduce TINY_RCU's memory footprint (thanks to Eric

34-70.	Use kfree_rcu() throughout the kernel.  This set of patches has
	Acked-by's, so will go up -tip.

71-86.	Ditto, but lacking Acked-by's.

For a testing-only version of this patchset from git, please see the
following subject-to-rebase branch:

git:// rcu/testing

							Thanx, Paul
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