Fix int->long and keep a reader count of 1 in the global GP variable

- Forgot a few migration from int to long
- Accelerate fast path by reading a GP variable which already has 1 reader
  count. This saves an increment in the fast path.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

diff --git a/urcu.c b/urcu.c
index 53c7f37677f762280b2a6337a6820bdf22c55faf..d4a06844885cde3da2d03092e3e9c45a939e0438 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -19,8 +19,12 @@
 
 pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-/* Global grace period counter */
-long urcu_gp_ctr;
+/*
+ * Global grace period counter.
+ * Contains the current RCU_GP_CTR_BIT.
+ * Also has a RCU_GP_CTR_BIT of 1, to accelerate the reader fast path.
+ */
+long urcu_gp_ctr = RCU_GP_COUNT;
 
 long __thread urcu_active_readers;
 
@@ -29,7 +33,7 @@ long __thread urcu_active_readers;
 
 struct reader_data {
        pthread_t tid;
-       int *urcu_active_readers;
+       long *urcu_active_readers;
 };
 
 #ifdef DEBUG_YIELD

diff --git a/urcu.h b/urcu.h
index 444d9cdba3346d987070dfa8fc68b78df4fe923f..9e9fea2b96fafa5c4688a1b1bf696284587df25f 100644 (file)
--- a/urcu.h
+++ b/urcu.h
@@ -179,7 +179,7 @@ extern long urcu_gp_ctr;
 
 extern long __thread urcu_active_readers;
 
-static inline int rcu_old_gp_ongoing(int *value)
+static inline int rcu_old_gp_ongoing(long *value)
 {
        long v;
 
@@ -200,7 +200,7 @@ static inline void rcu_read_lock(void)
        tmp = urcu_active_readers;
        debug_yield_read();
        if (likely(!(tmp & RCU_GP_CTR_NEST_MASK)))
-               urcu_active_readers = urcu_gp_ctr + RCU_GP_COUNT;
+               urcu_active_readers = urcu_gp_ctr;
        else
                urcu_active_readers = tmp + RCU_GP_COUNT;
        debug_yield_read();