pgbench: Improve time logic.

Instead of instr_time (struct timespec) and the INSTR_XXX macros,
introduce pg_time_usec_t and use integer arithmetic.  Don't include the
connection time in TPS unless using -C mode, but report it separately.

Author: Fabien COELHO <coelho@cri.ensmp.fr>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Discussion: https://postgr.es/m/20200227180100.zyvjwzcpiokfsqm2%40alap3.anarazel.de

doc/src/sgml/ref/pgbench.sgml

@@ -58,8 +58,10 @@ number of clients: 10
 number of threads: 1
 number of transactions per client: 1000
 number of transactions actually processed: 10000/10000
-tps = 85.184871 (including connections establishing)
-tps = 85.296346 (excluding connections establishing)
+latency average = 11.013 ms
+latency stddev = 7.351 ms
+initial connection time = 45.758 ms
+tps = 896.967014 (without initial connection time)
 </screen>
 
   The first six lines report some of the most important parameter
@@ -68,8 +70,7 @@ tps = 85.296346 (excluding connections establishing)
   and number of transactions per client); these will be equal unless the run
   failed before completion.  (In <option>-T</option> mode, only the actual
   number of transactions is printed.)
-  The last two lines report the number of transactions per second,
-  figured with and without counting the time to start database sessions.
+  The last line reports the number of transactions per second.
  </para>
 
   <para>
@@ -2257,22 +2258,22 @@ number of clients: 10
 number of threads: 1
 number of transactions per client: 1000
 number of transactions actually processed: 10000/10000
-latency average = 15.844 ms
-latency stddev = 2.715 ms
-tps = 618.764555 (including connections establishing)
-tps = 622.977698 (excluding connections establishing)
+latency average = 10.870 ms
+latency stddev = 7.341 ms
+initial connection time = 30.954 ms
+tps = 907.949122 (without initial connection time)
 statement latencies in milliseconds:
-        0.002  \set aid random(1, 100000 * :scale)
-        0.005  \set bid random(1, 1 * :scale)
-        0.002  \set tid random(1, 10 * :scale)
-        0.001  \set delta random(-5000, 5000)
-        0.326  BEGIN;
-        0.603  UPDATE pgbench_accounts SET abalance = abalance + :delta WHERE aid = :aid;
-        0.454  SELECT abalance FROM pgbench_accounts WHERE aid = :aid;
-        5.528  UPDATE pgbench_tellers SET tbalance = tbalance + :delta WHERE tid = :tid;
-        7.335  UPDATE pgbench_branches SET bbalance = bbalance + :delta WHERE bid = :bid;
-        0.371  INSERT INTO pgbench_history (tid, bid, aid, delta, mtime) VALUES (:tid, :bid, :aid, :delta, CURRENT_TIMESTAMP);
-        1.212  END;
+    0.001  \set aid random(1, 100000 * :scale)
+    0.001  \set bid random(1, 1 * :scale)
+    0.001  \set tid random(1, 10 * :scale)
+    0.000  \set delta random(-5000, 5000)
+    0.046  BEGIN;
+    0.151  UPDATE pgbench_accounts SET abalance = abalance + :delta WHERE aid = :aid;
+    0.107  SELECT abalance FROM pgbench_accounts WHERE aid = :aid;
+    4.241  UPDATE pgbench_tellers SET tbalance = tbalance + :delta WHERE tid = :tid;
+    5.245  UPDATE pgbench_branches SET bbalance = bbalance + :delta WHERE bid = :bid;
+    0.102  INSERT INTO pgbench_history (tid, bid, aid, delta, mtime) VALUES (:tid, :bid, :aid, :delta, CURRENT_TIMESTAMP);
+    0.974  END;
 </screen>
   </para>
 

src/include/portability/instr_time.h

@@ -253,4 +253,32 @@ GetTimerFrequency(void)
 #define INSTR_TIME_SET_CURRENT_LAZY(t) \
 	(INSTR_TIME_IS_ZERO(t) ? INSTR_TIME_SET_CURRENT(t), true : false)
 
+/*
+ * Simpler convenient interface
+ *
+ * The instr_time type is expensive when dealing with time arithmetic.
+ * Define a type to hold microseconds on top of this, suitable for
+ * benchmarking performance measures, eg in "pgbench".
+ *
+ * Type int64 is good enough for about 584500 years.
+ */
+typedef int64 pg_time_usec_t;
+
+static inline pg_time_usec_t
+pg_time_now(void)
+{
+	instr_time now;
+
+	INSTR_TIME_SET_CURRENT(now);
+	return (pg_time_usec_t) INSTR_TIME_GET_MICROSEC(now);
+}
+
+static inline void
+pg_time_now_lazy(pg_time_usec_t *now)
+{
+	if ((*now) == 0)
+		(*now) = pg_time_now();
+}
+
+#define PG_TIME_GET_DOUBLE(t) (0.000001 * (t))
 #endif							/* INSTR_TIME_H */

src/tools/pgindent/typedefs.list

@@ -3225,6 +3225,7 @@ pg_sha512_ctx
 pg_snapshot
 pg_stack_base_t
 pg_time_t
+pg_time_usec_t
 pg_tz
 pg_tz_cache
 pg_tzenum