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Message-Id: <20160927141016.6027-1-rui.teng@linux.vnet.ibm.com>
Date: Tue, 27 Sep 2016 22:10:16 +0800
From: Rui Teng <rui.teng@...ux.vnet.ibm.com>
To: linuxppc-dev@...ts.ozlabs.org, linux-kselftest@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Michael Ellerman <mpe@...erman.id.au>,
Shuah Khan <shuah@...nel.org>,
Anton Blanchard <anton@....ibm.com>,
Cyril Bur <cyrilbur@...il.com>,
Michael Neuling <mikey@...ling.org>,
Anton Blanchard <anton@....ibm.com>,
Rui Teng <rui.teng@...ux.vnet.ibm.com>
Subject: [PATCH] tools/testing/selftests/powerpc: Add Anton's null_syscall benchmark to the selftests
From: Anton Blanchard <anton@...ibm.com>
Pull in a version of Anton's null_syscall benchmark:
http://ozlabs.org/~anton/junkcode/null_syscall.c
Into tools/testing/selftests/powerpc/benchmarks.
Suggested-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Anton Blanchard <anton@...ibm.com>
Signed-off-by: Rui Teng <rui.teng@...ux.vnet.ibm.com>
---
.../testing/selftests/powerpc/benchmarks/Makefile | 2 +-
.../selftests/powerpc/benchmarks/null_syscall.c | 157 +++++++++++++++++++++
2 files changed, 158 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/powerpc/benchmarks/null_syscall.c
diff --git a/tools/testing/selftests/powerpc/benchmarks/Makefile b/tools/testing/selftests/powerpc/benchmarks/Makefile
index a9adfb7..545077f 100644
--- a/tools/testing/selftests/powerpc/benchmarks/Makefile
+++ b/tools/testing/selftests/powerpc/benchmarks/Makefile
@@ -1,4 +1,4 @@
-TEST_PROGS := gettimeofday context_switch mmap_bench futex_bench
+TEST_PROGS := gettimeofday context_switch mmap_bench futex_bench null_syscall
CFLAGS += -O2
diff --git a/tools/testing/selftests/powerpc/benchmarks/null_syscall.c b/tools/testing/selftests/powerpc/benchmarks/null_syscall.c
new file mode 100644
index 0000000..59c2f45
--- /dev/null
+++ b/tools/testing/selftests/powerpc/benchmarks/null_syscall.c
@@ -0,0 +1,157 @@
+/*
+ * Test null syscall performance
+ *
+ * Copyright (C) 2009-2015 Anton Blanchard <anton@...ibm.com>, IBM
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define NR_LOOPS 10000000
+
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <signal.h>
+
+static volatile int soak_done;
+unsigned long long clock_frequency;
+unsigned long long timebase_frequency;
+double timebase_multiplier;
+
+static inline unsigned long long mftb(void)
+{
+ unsigned long low;
+
+ asm volatile("mftb %0" : "=r" (low));
+
+ return low;
+}
+
+static void sigalrm_handler(int unused)
+{
+ soak_done = 1;
+}
+
+/*
+ * Use a timer instead of busy looping on clock_gettime() so we don't
+ * pollute profiles with glibc and VDSO hits.
+ */
+static void cpu_soak_usecs(unsigned long usecs)
+{
+ struct itimerval val;
+
+ memset(&val, 0, sizeof(val));
+ val.it_value.tv_usec = usecs;
+
+ signal(SIGALRM, sigalrm_handler);
+ setitimer(ITIMER_REAL, &val, NULL);
+
+ while (1) {
+ if (soak_done)
+ break;
+ }
+
+ signal(SIGALRM, SIG_DFL);
+}
+
+/*
+ * This only works with recent kernels where cpufreq modifies
+ * /proc/cpuinfo dynamically.
+ */
+static void get_proc_frequency(void)
+{
+ FILE *f;
+ char line[128];
+ char *p, *end;
+ unsigned long v;
+ double d;
+ char *override;
+
+ /* Try to get out of low power/low frequency mode */
+ cpu_soak_usecs(0.25 * 1000000);
+
+ f = fopen("/proc/cpuinfo", "r");
+ if (f == NULL)
+ return;
+
+ timebase_frequency = 0;
+
+ while (fgets(line, sizeof(line), f) != NULL) {
+ if (strncmp(line, "timebase", 8) == 0) {
+ p = strchr(line, ':');
+ if (p != NULL) {
+ v = strtoull(p + 1, &end, 0);
+ if (end != p + 1)
+ timebase_frequency = v;
+ }
+ }
+
+ if (((strncmp(line, "clock", 5) == 0) ||
+ (strncmp(line, "cpu MHz", 7) == 0))) {
+ p = strchr(line, ':');
+ if (p != NULL) {
+ d = strtod(p + 1, &end);
+ if (end != p + 1) {
+ /* Find fastest clock frequency */
+ if ((d * 1000000ULL) > clock_frequency)
+ clock_frequency = d * 1000000ULL;
+ }
+ }
+ }
+ }
+
+ fclose(f);
+
+ override = getenv("FREQUENCY");
+ if (override)
+ clock_frequency = strtoull(override, NULL, 10);
+
+ if (timebase_frequency)
+ timebase_multiplier = (double)clock_frequency
+ / timebase_frequency;
+ else
+ timebase_multiplier = 1;
+}
+
+static void do_null_syscall(unsigned long nr)
+{
+ unsigned long i;
+
+ for (i = 0; i < nr; i++)
+ getppid();
+}
+
+#define TIME(A, STR) \
+
+int main(void)
+{
+ unsigned long tb_start, tb_now;
+ struct timespec tv_start, tv_now;
+ unsigned long long elapsed_ns, elapsed_tb;
+
+ get_proc_frequency();
+
+ clock_gettime(CLOCK_MONOTONIC, &tv_start);
+ tb_start = mftb();
+
+ do_null_syscall(NR_LOOPS);
+
+ clock_gettime(CLOCK_MONOTONIC, &tv_now);
+ tb_now = mftb();
+
+ elapsed_ns = (tv_now.tv_sec - tv_start.tv_sec) * 1000000000ULL +
+ (tv_now.tv_nsec - tv_start.tv_nsec);
+ elapsed_tb = tb_now - tb_start;
+
+ printf("%10.2f ns %10.2f cycles\n", (float)elapsed_ns / NR_LOOPS,
+ (float)elapsed_tb * timebase_multiplier / NR_LOOPS);
+
+ return 0;
+}
--
2.7.4
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