rcx

commit 2064b054b1037824f2ad243f9dd86ae6c03f8a14
parent dd4e201390262f46d2b91b9815706a82561eb3d9
Author: robert <robertrussell.72001@gmail.com>
Date:   Wed, 10 Aug 2022 12:05:06 -0700

Add benchmarking module

Diffstat:
M
Makefile
 | 
4
+++-
M
inc/cext/all.h
 | 
1
+
A
inc/cext/bench.h
 | 
28
++++++++++++++++++++++++++++
A
src/bench.c
 | 
99
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

4 files changed, 131 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
@@ -4,6 +4,7 @@ include config.mk
 
 SRC =\
 	src/alloc.c\
+	src/bench.c\
 	src/log.c\
 	src/opt.c\
 	src/str.c\
@@ -16,9 +17,10 @@ libcext.a: $(SRC:.c=.o)
 	$(CC) -c -o $@ $(CFLAGS) $<
 
 src/alloc.o: src/alloc.c inc/cext/cext.h inc/cext/def.h inc/cext/alloc.h inc/cext/log.h config.mk
+src/bench.o: src/bench.c inc/cext/cext.h inc/cext/def.h inc/cext/bench.h inc/cext/log.h config.mk
 src/log.o: src/log.c inc/cext/cext.h inc/cext/def.h inc/cext/log.h config.mk
 src/opt.o: src/opt.c inc/cext/cext.h inc/cext/def.h inc/cext/opt.h config.mk
-src/str.o: src/str.c inc/cext/cext.h inc/cext/def.h inc/cext/str.h config.mk
+src/str.o: src/str.c inc/cext/cext.h inc/cext/def.h inc/cext/str.h config.mk # TODO missing deps
 src/utf8.o: src/utf8.c inc/cext/cext.h inc/cext/def.h inc/cext/utf8.h config.mk
 
 clean:
diff --git a/inc/cext/all.h b/inc/cext/all.h
@@ -1,3 +1,4 @@
+/* Everything except bench.h */
 #include "cext/alloc.h"
 #include "cext/cext.h"
 #include "cext/deque.h"
diff --git a/inc/cext/bench.h b/inc/cext/bench.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include "cext/def.h"
+
+/*
+Usage:
+	void my_benchmark(u64 N) {
+		<initialization (not timed)>
+		bench_start();
+		for (u64 i = 0; i < N; i++) {
+			<code to benchmark>
+		}
+		bench_stop();
+		<cleanup (not timed)>
+	}
+	int main(void) {
+		bench("my benchmark", my_benchmark, 3*SECONDS);
+	}
+Note that <code to benchmark> can contain calls to bench_stop and bench_start
+to pause and restart timing.
+*/
+
+#define MILLISECONDS 1000000ULL
+#define SECONDS 1000000000ULL
+
+void bench(char *name, void (*fn)(u64 N), u64 goalns);
+void bench_start(void);
+void bench_stop(void);
diff --git a/src/bench.c b/src/bench.c
@@ -0,0 +1,99 @@
+#define _POSIX_C_SOURCE 199309L /* clock_gettime */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "cext/bench.h"
+#include "cext/cext.h"
+#include "cext/log.h"
+
+#ifndef _POSIX_THREAD_CPUTIME
+#error "Need CLOCK_PROCESS_CPUTIME_ID"
+#endif
+
+#define MAXN 1000000000ULL
+
+static u64 run(void (*fn)(u64 N), u64 N);
+static u64 requiredN(u64 prevN, u64 prevns, u64 goalns);
+static void printnsop(u64 N, u64 ns);
+
+static bool started; /* Has bench_start been called? */
+static bool active;  /* Is the timer currently on? */
+static struct timespec start;
+static u64 accumns;
+
+u64
+run(void (*fn)(u64 N), u64 N) {
+	started = active = false;
+	accumns = 0;
+	fn(N);
+	if (active || !started)
+		fatalf("bench misuse");
+	return accumns;
+}
+
+u64
+requiredN(u64 prevN, u64 prevns, u64 goalns) {
+	/* This is pretty much copied from Go's testing package. */
+	u64 N = prevN * goalns / (prevns == 0 ? 1 : prevns);
+	N += N/5;              /* Overestimate by 1.2x. */
+	N = MIN(N, 100*prevN); /* Grow slowly, in case prevns is inaccurate. */
+	N = MAX(N, prevN+1);   /* Do at least one more run, */
+	N = MIN(N, MAXN);      /* but don't do too many. */
+	return N;
+}
+
+void
+printnsop(u64 N, u64 ns) {
+	double nsop = (double) ns / N;
+
+	/* This is pretty much copied from Go's testing package. */
+	char *format;
+	if (nsop == 0 || nsop >= 99.95) format = "%10.0f ns/op";
+	else if (nsop >= 9.995)         format = "%12.1f ns/op";
+	else if (nsop >= 0.9995)        format = "%13.2f ns/op";
+	else if (nsop >= 0.09995)       format = "%14.3f ns/op";
+	else if (nsop >= 0.009995)      format = "%15.4f ns/op";
+	else if (nsop >= 0.0009995)     format = "%16.5f ns/op";
+	else                            format = "%17.6f ns/op";
+
+	fprintf(stderr, format, nsop);
+}
+
+void
+bench(char *name, void (*fn)(u64 N), u64 goalns) {
+	run(fn, 1); /* Warmup */
+	u64 N = 1;
+	u64 ns;
+	while ((ns = run(fn, N)) < goalns && N < MAXN)
+		N = requiredN(N, ns, goalns);
+
+	fprintf(stderr, "benchmark: %-25s%10"PRId64" iters  ", name, N);
+	printnsop(N, ns);
+	fprintf(stderr, "\n");
+}
+
+void
+bench_start(void) {
+	if (active)
+		return;
+	active = true;
+	started = true;
+	if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start) < 0)
+		fatalf("clock_gettime: %s", strerror(errno));
+}
+
+void
+bench_stop(void) {
+	if (!active)
+		return;
+	struct timespec stop;
+	if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &stop) < 0)
+		fatalf("clock_gettime: %s", strerror(errno));
+	active = false;
+	accumns += (stop.tv_sec - start.tv_sec) * 1000000000ULL
+		+ (stop.tv_nsec - start.tv_nsec);
+}