INSTALL.md: Fix shell command line formatting.

[cascardo/ovs.git] / lib / coverage.c

diff --git a/lib/coverage.c b/lib/coverage.c
index fe97d69..9584cac 100644 (file)
--- a/lib/coverage.c
+++ b/lib/coverage.c
@@ -24,7 +24,7 @@
 #include "timeval.h"
 #include "unixctl.h"
 #include "util.h"
-#include "vlog.h"
+#include "openvswitch/vlog.h"
 
 VLOG_DEFINE_THIS_MODULE(coverage);
 
@@ -245,9 +245,14 @@ coverage_read(struct svec *lines)
 
 /* Runs approximately every COVERAGE_CLEAR_INTERVAL amount of time to
  * synchronize per-thread counters with global counters. Every thread maintains
- * a separate timer to ensure all counters are periodically aggregated. */
-void
-coverage_clear(void)
+ * a separate timer to ensure all counters are periodically aggregated.
+ *
+ * Uses 'ovs_mutex_trylock()' if 'trylock' is true.  This is to prevent
+ * multiple performance-critical threads contending over the 'coverage_mutex'.
+ *
+ * */
+static void
+coverage_clear__(bool trylock)
 {
     long long int now, *thread_time;
 
@@ -262,7 +267,15 @@ coverage_clear(void)
     if (now >= *thread_time) {
         size_t i;
 
-        ovs_mutex_lock(&coverage_mutex);
+        if (trylock) {
+            /* Returns if cannot acquire lock. */
+            if (ovs_mutex_trylock(&coverage_mutex)) {
+                return;
+            }
+        } else {
+            ovs_mutex_lock(&coverage_mutex);
+        }
+
         for (i = 0; i < n_coverage_counters; i++) {
             struct coverage_counter *c = coverage_counters[i];
             c->total += c->count();
@@ -272,6 +285,18 @@ coverage_clear(void)
     }
 }
 
+void
+coverage_clear(void)
+{
+    coverage_clear__(false);
+}
+
+void
+coverage_try_clear(void)
+{
+    coverage_clear__(true);
+}
+
 /* Runs approximately every COVERAGE_RUN_INTERVAL amount of time to update the
  * coverage counters' 'min' and 'hr' array.  'min' array is for cumulating
  * per second counts into per minute count.  'hr' array is for cumulating per