Fix: high cpu usage in synchronize_rcu with long RCU read-side C.S.

[urcu.git] / urcu-bp.c

diff --git a/urcu-bp.c b/urcu-bp.c
index 369bebab466919dae4fa1fa802ccd0b3723d7bd8..1856d3fc76fa1ec31a644ea9fa326a4ab48182f8 100644 (file)
--- a/urcu-bp.c
+++ b/urcu-bp.c
@@ -79,8 +79,8 @@ void *mremap_wrapper(void *old_address, size_t old_size,
 }
 #endif
 
-/* Sleep delay in us */
-#define RCU_SLEEP_DELAY                1000
+/* Sleep delay in ms */
+#define RCU_SLEEP_DELAY_MS     10
 #define INIT_NR_THREADS                8
 #define ARENA_INIT_ALLOC               \
        sizeof(struct registry_chunk)   \
@@ -169,7 +169,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
                        struct cds_list_head *cur_snap_readers,
                        struct cds_list_head *qsreaders)
 {
-       int wait_loops = 0;
+       unsigned int wait_loops = 0;
        struct rcu_reader *index, *tmp;
 
        /*
@@ -178,7 +178,9 @@ static void wait_for_readers(struct cds_list_head *input_readers,
         * rcu_gp.ctr value.
         */
        for (;;) {
-               wait_loops++;
+               if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
+                       wait_loops++;
+
                cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
                        switch (rcu_reader_state(&index->ctr)) {
                        case RCU_READER_ACTIVE_CURRENT:
@@ -205,8 +207,8 @@ static void wait_for_readers(struct cds_list_head *input_readers,
                if (cds_list_empty(input_readers)) {
                        break;
                } else {
-                       if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS)
-                               usleep(RCU_SLEEP_DELAY);
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS)
+                               (void) poll(NULL, 0, RCU_SLEEP_DELAY_MS);
                        else
                                caa_cpu_relax();
                }