The usefulness of having a standard way of testing syscall performance
has come up from time to time[0]. Furthermore, some of our testing
machinery (such as 'mmtests') already makes use of a simplified version
of the microbenchmark. This patch mainly takes the same idea to measure
syscall throughput compatible with 'perf-bench' via getppid(2), yet
without any of the additional template stuff from Ingo's version (based
on numa.c). The code is identical to what mmtests uses.

https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1067469.html

Signed-off-by: Davidlohr Bueso <dbu...@suse.de>
---
 tools/perf/bench/Build     |  1 +
 tools/perf/bench/bench.h   |  1 +
 tools/perf/bench/syscall.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/builtin-bench.c |  8 +++++
 4 files changed, 90 insertions(+)
 create mode 100644 tools/perf/bench/syscall.c

diff --git a/tools/perf/bench/Build b/tools/perf/bench/Build
index e4e321b6f883..839f9b790587 100644
--- a/tools/perf/bench/Build
+++ b/tools/perf/bench/Build
@@ -1,5 +1,6 @@
 perf-y += sched-messaging.o
 perf-y += sched-pipe.o
+perf-y += syscall.o
 perf-y += mem-functions.o
 perf-y += futex-hash.o
 perf-y += futex-wake.o
diff --git a/tools/perf/bench/bench.h b/tools/perf/bench/bench.h
index fddb3ced9db6..31ad3283d41b 100644
--- a/tools/perf/bench/bench.h
+++ b/tools/perf/bench/bench.h
@@ -29,6 +29,7 @@
 int bench_numa(int argc, const char **argv);
 int bench_sched_messaging(int argc, const char **argv);
 int bench_sched_pipe(int argc, const char **argv);
+int bench_syscall_basic(int argc, const char **argv);
 int bench_mem_memcpy(int argc, const char **argv);
 int bench_mem_memset(int argc, const char **argv);
 int bench_futex_hash(int argc, const char **argv);
diff --git a/tools/perf/bench/syscall.c b/tools/perf/bench/syscall.c
new file mode 100644
index 000000000000..149129cca639
--- /dev/null
+++ b/tools/perf/bench/syscall.c
@@ -0,0 +1,80 @@
+/*
+ *
+ * syscall.c
+ *
+ * syscall: Benchmark for system call performance
+ */
+#include "../perf.h"
+#include "../util/util.h"
+#include <subcmd/parse-options.h>
+#include "../builtin.h"
+#include "bench.h"
+
+#include <stdio.h>
+#include <locale.h>
+#include <sys/time.h>
+#include <sys/syscall.h>
+
+#define LOOPS_DEFAULT 10000000
+static int loops = LOOPS_DEFAULT;
+
+static const struct option options[] = {
+       OPT_INTEGER('l', "loop",        &loops,         "Specify number of 
loops"),
+       OPT_END()
+};
+
+static const char * const bench_syscall_usage[] = {
+       "perf bench syscall <options>",
+       NULL
+};
+
+int bench_syscall_basic(int argc, const char **argv)
+{
+       struct timeval start, stop, diff;
+       unsigned long long result_usec = 0;
+       int i;
+
+       argc = parse_options(argc, argv, options, bench_syscall_usage, 0);
+
+       gettimeofday(&start, NULL);
+
+       for (i = 0; i < loops; i++)
+               getppid();
+
+       gettimeofday(&stop, NULL);
+       timersub(&stop, &start, &diff);
+
+       switch (bench_format) {
+       case BENCH_FORMAT_DEFAULT:
+               setlocale(LC_NUMERIC, "");
+               printf("# Executed %'d getppid() calls\n", loops);
+
+               result_usec = diff.tv_sec * 1000000;
+               result_usec += diff.tv_usec;
+
+               printf(" %14s: %lu.%03lu [sec]\n\n", "Total time",
+                      diff.tv_sec,
+                      (unsigned long) (diff.tv_usec/1000));
+
+               printf(" %14lf usecs/op\n",
+                      (double)result_usec / (double)loops);
+               printf(" %'14d ops/sec\n",
+                      (int)((double)loops /
+                            ((double)result_usec / (double)1000000)));
+               break;
+
+       case BENCH_FORMAT_SIMPLE:
+               printf("%lu.%03lu\n",
+                      diff.tv_sec,
+                      (unsigned long) (diff.tv_usec / 1000));
+               break;
+
+       default:
+               /* reaching here is something disaster */
+               fprintf(stderr, "Unknown format:%d\n", bench_format);
+               exit(1);
+               break;
+       }
+
+       return 0;
+}
diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c
index 334c77ffc1d9..4e9dd0f4eced 100644
--- a/tools/perf/builtin-bench.c
+++ b/tools/perf/builtin-bench.c
@@ -11,6 +11,7 @@
  * Available benchmark collection list:
  *
  *  sched ... scheduler and IPC performance
+ *  syscall ... System call performance
  *  mem   ... memory access performance
  *  numa  ... NUMA scheduling and MM performance
  *  futex ... Futex performance
@@ -50,6 +51,12 @@ static struct bench sched_benchmarks[] = {
        { NULL,         NULL,                                           NULL    
                }
 };
 
+static struct bench syscall_benchmarks[] = {
+       { "basic",      "Benchmark for basic getppid() system calls",   
bench_syscall_basic     },
+       { "all",        "Run all syscall benchmarks",                   NULL    
                },
+       { NULL,         NULL,                                           NULL    
                },
+};
+
 static struct bench mem_benchmarks[] = {
        { "memcpy",     "Benchmark for memcpy() functions",             
bench_mem_memcpy        },
        { "memset",     "Benchmark for memset() functions",             
bench_mem_memset        },
@@ -85,6 +92,7 @@ struct collection {
 
 static struct collection collections[] = {
        { "sched",      "Scheduler and IPC benchmarks",                 
sched_benchmarks        },
+       { "syscall",    "System call benchmarks",                       
syscall_benchmarks      },
        { "mem",        "Memory access benchmarks",                     
mem_benchmarks          },
 #ifdef HAVE_LIBNUMA_SUPPORT
        { "numa",       "NUMA scheduling and MM benchmarks",            
numa_benchmarks         },
-- 
2.16.4

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