At Thu, 17 Sep 2020 17:59:45 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in
> Sigh.. I fixed some more wordings.
The condition "all clients took the same time to establish a
connection" is not needed for the transformation, and an intermediate
expression was wrong. Fixed them.
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
From 802c06d95aebdb8a4ed4e3adc4a6c74d9675c625 Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horikyoga.ntt@gmail.com>
Date: Thu, 17 Sep 2020 17:20:10 +0900
Subject: [PATCH v4] Fix latency and tps calculation of pgbench
Fix the calculation for "latency average" and the "tps excluding
connections establishing" not to wrongly affected by connections
establishing time.
---
src/bin/pgbench/pgbench.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index 663d7d292a..4164a546e1 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -5194,16 +5194,34 @@ printResults(StatsData *total, instr_time total_time,
instr_time conn_total_time, int64 latency_late)
{
double time_include,
+ time_exclude,
tps_include,
tps_exclude;
int64 ntx = total->cnt - total->skipped;
time_include = INSTR_TIME_GET_DOUBLE(total_time);
+ /*
+ * conn_total_time is the sum of the time each client took to establish a
+ * connection. In the multi-threaded case, all clients run on a thread wait
+ * for all the clients to establish a connection. So the actual total
+ * connection time of a thread is thread->conn_time * thread->nstate. Thus
+ * the total time took for connection establishment is:
+ *
+ * sum(thread->conn_time * thread->nstate) / nclients
+ *
+ * Assuming clients are distributed equally to threads, the expression is
+ * approximated as:
+ *
+ * sum(thread->conn_time) * (nclients/nthreads) / nclients
+ * = conn_total_time / nthreads
+ */
+ time_exclude = (time_include -
+ (INSTR_TIME_GET_DOUBLE(conn_total_time) / nthreads));
+
/* tps is about actually executed transactions */
tps_include = ntx / time_include;
- tps_exclude = ntx /
- (time_include - (INSTR_TIME_GET_DOUBLE(conn_total_time) / nclients));
+ tps_exclude = ntx / time_exclude;
/* Report test parameters. */
printf("transaction type: %s\n",
@@ -5249,7 +5267,7 @@ printResults(StatsData *total, instr_time total_time,
{
/* no measurement, show average latency computed from run time */
printf("latency average = %.3f ms\n",
- 1000.0 * time_include * nclients / total->cnt);
+ 1000.0 * time_exclude * nclients / total->cnt);
}
if (throttle_delay)
--
2.18.4
