28 Aug, 2010

1 commit

• dd7c4d897   rcu: performance fixes to TINY_PREEMPT_RCU callback checking ... Browse Code »

  This commit tightens up checks in rcu_preempt_check_callbacks() to avoid
  unnecessary special handling at rcu_read_unlock() time.

  Signed-off-by: Paul E. McKenney

  Paul E. McKenney

  2010-08-28 01:51:17 +0800  

21 Aug, 2010

1 commit

• a3dc3fb16   rcu: repair code-duplication FIXMEs ... Browse Code »

  Combine the duplicate definitions of ULONG_CMP_GE(), ULONG_CMP_LT(),
  and rcu_preempt_depth() into include/linux/rcupdate.h.

  Signed-off-by: Paul E. McKenney

  Paul E. McKenney

  2010-08-21 00:00:13 +0800  

20 Aug, 2010

1 commit

• a57eb940d   rcu: Add a TINY_PREEMPT_RCU ... Browse Code »

  Implement a small-memory-footprint uniprocessor-only implementation of
  preemptible RCU. This implementation uses but a single blocked-tasks
  list rather than the combinatorial number used per leaf rcu_node by
  TREE_PREEMPT_RCU, which reduces memory consumption and greatly simplifies
  processing. This version also takes advantage of uniprocessor execution
  to accelerate grace periods in the case where there are no readers.

  The general design is otherwise broadly similar to that of TREE_PREEMPT_RCU.

  This implementation is a step towards having RCU implementation driven
  off of the SMP and PREEMPT kernel configuration variables, which can
  happen once this implementation has accumulated sufficient experience.

  Removed ACCESS_ONCE() from __rcu_read_unlock() and added barrier() as
  suggested by Steve Rostedt in order to avoid the compiler-reordering
  issue noted by Mathieu Desnoyers (http://lkml.org/lkml/2010/8/16/183).

  As can be seen below, CONFIG_TINY_PREEMPT_RCU represents almost 5Kbyte
  savings compared to CONFIG_TREE_PREEMPT_RCU. Of course, for non-real-time
  workloads, CONFIG_TINY_RCU is even better.

  CONFIG_TREE_PREEMPT_RCU

  text data bss dec filename
  13 0 0 13 kernel/rcupdate.o
  6170 825 28 7023 kernel/rcutree.o
  ----
  7026 Total

  CONFIG_TINY_PREEMPT_RCU

  text data bss dec filename
  13 0 0 13 kernel/rcupdate.o
  2081 81 8 2170 kernel/rcutiny.o
  ----
  2183 Total

  CONFIG_TINY_RCU (non-preemptible)

  text data bss dec filename
  13 0 0 13 kernel/rcupdate.o
  719 25 0 744 kernel/rcutiny.o
  ---
  757 Total

  Requested-by: Loïc Minier
  Signed-off-by: Paul E. McKenney

  Paul E. McKenney

  2010-08-20 23:55:00 +0800  

11 May, 2010

1 commit

• bbad93798   rcu: slim down rcutiny by removing rcu_scheduler_active and friends ... Browse Code »

  TINY_RCU does not need rcu_scheduler_active unless CONFIG_DEBUG_LOCK_ALLOC.
  So conditionally compile rcu_scheduler_active in order to slim down
  rcutiny a bit more. Also gets rid of an EXPORT_SYMBOL_GPL, which is
  responsible for most of the slimming.

  Signed-off-by: Paul E. McKenney

  Paul E. McKenney

  2010-05-11 02:08:34 +0800