From 9928758f916973fe371646228958bcc85bb2e186 Mon Sep 17 00:00:00 2001
From: Rodrigo Arias <rodrigo.arias@bsc.es>
Date: Fri, 13 Jan 2023 11:27:13 +0100
Subject: [PATCH] Test bay_find speed compared with direct access

---
 src/emu/chan.c             |   8 +--
 test/unit/CMakeLists.txt   |   1 +
 test/unit/bay-hash-speed.c | 117 +++++++++++++++++++++++++++++++++++++
 3 files changed, 121 insertions(+), 5 deletions(-)
 create mode 100644 test/unit/bay-hash-speed.c

diff --git a/src/emu/chan.c b/src/emu/chan.c
index 3b56556..95998cc 100644
--- a/src/emu/chan.c
+++ b/src/emu/chan.c
@@ -1,8 +1,6 @@
 /* Copyright (c) 2021-2022 Barcelona Supercomputing Center (BSC)
  * SPDX-License-Identifier: GPL-3.0-or-later */
 
-#define ENABLE_DEBUG
-
 #include "chan.h"
 #include "common.h"
 #include <string.h>
@@ -94,9 +92,9 @@ chan_set(struct chan *chan, struct value value)
 		return -1;
 	}
 
-	char buf[128];
-	dbg("chan_set %s: sets value to %s\n",
-			chan->name, value_str(value, buf));
+	//char buf[128];
+	//dbg("chan_set %s: sets value to %s\n",
+	//		chan->name, value_str(value, buf));
 	chan->data.value = value;
 
 	if (set_dirty(chan) != 0) {
diff --git a/test/unit/CMakeLists.txt b/test/unit/CMakeLists.txt
index 75aa0a7..58b5a4e 100644
--- a/test/unit/CMakeLists.txt
+++ b/test/unit/CMakeLists.txt
@@ -10,5 +10,6 @@
 #unit_test(tbm_trace.c)
 unit_test(chan.c)
 unit_test(bay.c)
+unit_test(bay-hash-speed.c)
 unit_test(mux.c)
 unit_test(value.c)
diff --git a/test/unit/bay-hash-speed.c b/test/unit/bay-hash-speed.c
new file mode 100644
index 0000000..60055da
--- /dev/null
+++ b/test/unit/bay-hash-speed.c
@@ -0,0 +1,117 @@
+#define _POSIX_C_SOURCE 200112L
+
+#include "emu/bay.h"
+#include "common.h"
+#include <time.h>
+
+#define N 10000
+#define BASE "testchannelultramegahyperverylongname"
+
+struct chan *channels = NULL;
+int64_t dummy_value = 1;
+
+static double
+get_time(void)
+{
+	struct timespec ts;
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	return (double) ts.tv_sec + (double) ts.tv_nsec * 1.0e-9;
+}
+
+static void
+populate(struct bay *bay)
+{
+	char name[MAX_CHAN_NAME];
+
+	channels = calloc(N, sizeof(struct chan));
+	if (channels == NULL)
+		die("calloc failed\n");
+
+	for (long i = 0; i < N; i++) {
+		sprintf(name, "%s.%ld", BASE, i);
+		chan_init(&channels[i], CHAN_SINGLE, name);
+		if (bay_register(bay, &channels[i]) != 0)
+			die("bay_register failed\n");
+	}
+}
+
+static void
+dummy_work(struct chan *c)
+{
+	if (chan_set(c, value_int64(dummy_value++)) != 0)
+		die("chan_set failed\n");
+	if (chan_flush(c) != 0)
+		die("chan_flush failed\n");
+}
+
+static double
+measure_hash(struct bay *bay)
+{
+	double t0 = get_time();
+	double T = 5.0;
+	double t1 = t0 + T;
+
+	char name[MAX_CHAN_NAME];
+	long nlookups = 0;
+	srand(1);
+
+	while (get_time() < t1) {
+		long i = rand() % N;
+		sprintf(name, "%s.%ld", BASE, i);
+		struct chan *c = bay_find(bay, name);
+		if (c == NULL)
+			die("bay_find failed\n");
+		dummy_work(c);
+		nlookups++;
+	}
+
+	double speed = (double) nlookups / T;
+
+	err("bay_find: %e lookups/s\n", speed);
+	return speed;
+}
+
+static double
+measure_direct(void)
+{
+	double t0 = get_time();
+	double T = 5.0;
+	double t1 = t0 + T;
+
+	long nlookups = 0;
+	srand(1);
+
+	while (get_time() < t1) {
+		long i = rand() % N;
+		dummy_work(&channels[i]);
+		nlookups++;
+	}
+
+	double speed = (double) nlookups / T;
+
+	err("direct: %e lookups/s\n", speed);
+	return speed;
+}
+
+static void
+test_speed(struct bay *bay)
+{
+	double hash = measure_hash(bay);
+	double direct = measure_direct();
+	double slowdown = hash / direct;
+	err("slowdown speed_hash/speed_direct = %f\n", slowdown);
+
+	if (slowdown < 0.2)
+		die("hash speed is too slow\n");
+}
+
+int main(void)
+{
+	struct bay bay;
+	bay_init(&bay);
+
+	populate(&bay);
+	test_speed(&bay);
+
+	return 0;
+}