Exclude queries executed by background threads from statistic reports.

src/db_driver.c

@@ -192,10 +192,8 @@ static void db_init(void)
   /* Initialize timers if in debug mode */
   if (db_globals.debug)
   {
-    exec_timers = (sb_timer_t *) malloc(sb_globals.threads *
-                                        sizeof(sb_timer_t));
-    fetch_timers = (sb_timer_t *) malloc(sb_globals.threads *
-                                         sizeof(sb_timer_t));
+    exec_timers = sb_alloc_per_thread_array(sizeof(sb_timer_t));
+    fetch_timers = sb_alloc_per_thread_array(sizeof(sb_timer_t));
   }
 
   db_reset_stats();

src/sb_counter.c

@@ -34,10 +34,7 @@ int sb_counters_init(void)
 {
   SB_COMPILE_TIME_ASSERT(sizeof(sb_counters_t) % CK_MD_CACHELINE == 0);
 
-  sb_counters = sb_memalign(sb_globals.threads * sizeof(sb_counters_t),
-                            CK_MD_CACHELINE);
-
-  memset(sb_counters, 0, sb_globals.threads * sizeof(sb_counters_t));
+  sb_counters = sb_alloc_per_thread_array(sizeof(sb_counters_t));
 
   return sb_counters == NULL;
 }

src/sysbench.c

@@ -85,6 +85,12 @@
 /* Wait at most this number of seconds for worker threads to initialize */
 #define THREAD_INIT_TIMEOUT 30
 
+/*
+  Extra thread ID assigned to background threads. This may be used as an index
+  into per-thread arrays (see comment in sb_alloc_per_thread_array().
+*/
+#define SB_BACKGROUND_THREAD_ID sb_globals.threads
+
 /* General options */
 sb_arg_t general_args[] =
 {
@@ -892,6 +898,8 @@ static void *eventgen_thread_proc(void *arg)
 
   (void)arg; /* unused */
 
+  sb_tls_thread_id = SB_BACKGROUND_THREAD_ID;
+
   /* Initialize thread-local RNG state */
   sb_rand_thread_init();
 
@@ -959,6 +967,8 @@ static void *report_thread_proc(void *arg)
 
   (void)arg; /* unused */
 
+  sb_tls_thread_id = SB_BACKGROUND_THREAD_ID;
+
   /* Initialize thread-local RNG state */
   sb_rand_thread_init();
 
@@ -1007,6 +1017,8 @@ static void *checkpoints_thread_proc(void *arg)
 
   (void)arg; /* unused */
 
+  sb_tls_thread_id = SB_BACKGROUND_THREAD_ID;
+
   /* Initialize thread-local RNG state */
   sb_rand_thread_init();
 
@@ -1392,10 +1404,9 @@ static int init(void)
   }
 
   /* Initialize timers */
-  timers = sb_memalign(sb_globals.threads * sizeof(sb_timer_t),
-                       CK_MD_CACHELINE);
-  timers_copy = sb_memalign(sb_globals.threads * sizeof(sb_timer_t),
-                            CK_MD_CACHELINE);
+  timers = sb_alloc_per_thread_array(sizeof(sb_timer_t));
+  timers_copy = sb_alloc_per_thread_array(sizeof(sb_timer_t));
+
   if (timers == NULL || timers_copy == NULL)
   {
     log_text(LOG_FATAL, "Memory allocation failure");
@@ -1604,3 +1615,29 @@ void sb_print_test_options(void)
   if (current_test != NULL)
     sb_print_options(current_test->args);
 }
+
+/*
+  Allocate an array of objects of the specified size for all threads, both
+  worker and background ones.
+*/
+
+void *sb_alloc_per_thread_array(size_t size)
+{
+  /*
+    We want to exclude queries executed by background threads from statistics
+    generated for worker threads.
+
+    To simplify code, we allocate all timers and counters for all worker threads
+    + possible background threads created by sysbench for statistic reports,
+    etc. When executing requests from background threads, extra array slots will
+    be used (it depends on the assigned ID for each thread). When aggregating
+    counters and timers, we only consider slots in the range [0,
+    sb_globals.threads - 1], i.e. ignore statistics generated by background
+    threads. Currently we assign the same single thread ID for all background
+    threads, so they also share the same single slot in each allocated array.
+  */
+  void *ptr = sb_memalign((sb_globals.threads + 1) * size, CK_MD_CACHELINE);
+  memset(ptr, 0, size);
+
+  return ptr;
+}

src/sysbench.h

@@ -232,4 +232,10 @@ void sb_report_intermediate(sb_stat_t *stat);
 /* Default cumulative reports handler */
 void sb_report_cumulative(sb_stat_t *stat);
 
+/*
+  Allocate an array of objects of the specified size for all threads, both
+  worker and background ones.
+*/
+void *sb_alloc_per_thread_array(size_t size);
+
 #endif