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| author |   Tejun Heo <tj@kernel.org> | 2010-11-22 21:36:11 -0800 |
|---|---|---|
| committer |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-12-17 12:34:08 -0800 |
| commit | e27fc9641e8ddc8146f8e01f06e5eba2469698de (patch) | |
| tree | 5cff4c23cb113b901718d9c0f4a6e3081f3173bd /include/linux/rcupdate.h | |
| parent | rcu: Make synchronize_srcu_expedited() fast if running readers (diff) | |
| download | linux-dev-e27fc9641e8ddc8146f8e01f06e5eba2469698de.tar.xz linux-dev-e27fc9641e8ddc8146f8e01f06e5eba2469698de.zip | |
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.h | 2 |
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)) |