From e27fc9641e8ddc8146f8e01f06e5eba2469698de Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 22 Nov 2010 21:36:11 -0800 Subject: 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 Signed-off-by: Paul E. McKenney --- include/linux/rcupdate.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/rcupdate.h') 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)) -- cgit v1.2.3