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qsbr: save two full smp_mb() when the writer is also a reader.
[urcu.git]
/
urcu-qsbr.c
diff --git
a/urcu-qsbr.c
b/urcu-qsbr.c
index ccecab4e7b02b63d80f6c87085486dee0a5452f5..3f21be3160731979b6f39455b1202ccf00849237 100644
(file)
--- a/
urcu-qsbr.c
+++ b/
urcu-qsbr.c
@@
-106,11
+106,6
@@
static void force_mb_single_thread(struct reader_registry *index)
}
#endif /* #ifdef HAS_INCOHERENT_CACHES */
}
#endif /* #ifdef HAS_INCOHERENT_CACHES */
-static void force_mb_all_threads(void)
-{
- smp_mb();
-}
-
static void wait_for_quiescent_state(void)
{
struct reader_registry *index;
static void wait_for_quiescent_state(void)
{
struct reader_registry *index;
@@
-122,8
+117,7
@@
static void wait_for_quiescent_state(void)
*/
for (index = registry; index < registry + num_readers; index++) {
#ifndef HAS_INCOHERENT_CACHES
*/
for (index = registry; index < registry + num_readers; index++) {
#ifndef HAS_INCOHERENT_CACHES
- while (rcu_gp_ongoing(index->rcu_reader_qs_gp) &&
- (*index->rcu_reader_qs_gp - urcu_gp_ctr < 0))
+ while (rcu_gp_ongoing(index->rcu_reader_qs_gp))
cpu_relax();
#else /* #ifndef HAS_INCOHERENT_CACHES */
int wait_loops = 0;
cpu_relax();
#else /* #ifndef HAS_INCOHERENT_CACHES */
int wait_loops = 0;
@@
-131,8
+125,7
@@
static void wait_for_quiescent_state(void)
* BUSY-LOOP. Force the reader thread to commit its
* rcu_reader_qs_gp update to memory if we wait for too long.
*/
* BUSY-LOOP. Force the reader thread to commit its
* rcu_reader_qs_gp update to memory if we wait for too long.
*/
- while (rcu_gp_ongoing(index->rcu_reader_qs_gp) &&
- (*index->rcu_reader_qs_gp - urcu_gp_ctr < 0)) {
+ while (rcu_gp_ongoing(index->rcu_reader_qs_gp)) {
if (wait_loops++ == KICK_READER_LOOPS) {
force_mb_single_thread(index);
wait_loops = 0;
if (wait_loops++ == KICK_READER_LOOPS) {
force_mb_single_thread(index);
wait_loops = 0;
@@
-155,18
+148,18
@@
void synchronize_rcu(void)
* our own quiescent state. This allows using synchronize_rcu() in
* threads registered as readers.
*/
* our own quiescent state. This allows using synchronize_rcu() in
* threads registered as readers.
*/
+ smp_mb();
if (was_online)
if (was_online)
-
_rcu_thread_offline(
);
+
STORE_SHARED(rcu_reader_qs_gp, 0
);
internal_urcu_lock();
internal_urcu_lock();
- force_mb_all_threads();
- urcu_gp_ctr += 2;
+ STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr + 2);
wait_for_quiescent_state();
wait_for_quiescent_state();
- force_mb_all_threads();
internal_urcu_unlock();
if (was_online)
internal_urcu_unlock();
if (was_online)
- _rcu_thread_online();
+ _STORE_SHARED(rcu_reader_qs_gp, LOAD_SHARED(urcu_gp_ctr) + 1);
+ smp_mb();
}
/*
}
/*
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