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authorTejun Heo <tj@kernel.org>2010-11-23 08:36:11 +0300
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-12-17 23:34:08 +0300
commite27fc9641e8ddc8146f8e01f06e5eba2469698de (patch)
tree5cff4c23cb113b901718d9c0f4a6e3081f3173bd /include/linux/rcupdate.h
parent46fdb0937f26124700fc9fc80da4776330cc00d3 (diff)
downloadlinux-e27fc9641e8ddc8146f8e01f06e5eba2469698de.tar.xz
rcu: increase synchronize_sched_expedited() batching
The fix in commit #6a0cc49 requires more than three concurrent instances of synchronize_sched_expedited() before batching is possible. This patch uses a ticket-counter-like approach that is also not unrelated to Lai Jiangshan's Ring RCU to allow sharing of expedited grace periods even when there are only two concurrent instances of synchronize_sched_expedited(). This commit builds on Tejun's original posting, which may be found at http://lkml.org/lkml/2010/11/9/204, adding memory barriers, avoiding overflow of signed integers (other than via atomic_t), and fixing the detection of batching. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/linux/rcupdate.h')
-rw-r--r--include/linux/rcupdate.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 49e8e16308e1..af5614856285 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -47,6 +47,8 @@
extern int rcutorture_runnable; /* for sysctl */
#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
+#define UINT_CMP_GE(a, b) (UINT_MAX / 2 >= (a) - (b))
+#define UINT_CMP_LT(a, b) (UINT_MAX / 2 < (a) - (b))
#define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b))
#define ULONG_CMP_LT(a, b) (ULONG_MAX / 2 < (a) - (b))