[PATCH v3 2/3] benchtests: Add pthread adaptive spin mutex microbenchmark

[Kemi Wang <kemi dot wang at intel dot com>]

Add a microbenchmark for measuring mutex lock and unlock performance with
varying numbers of threads and varying size of a critical section. The
benchmark leverages the mutex lock and unlock operation for protecting the
critical section and measures the minimum iterations, the maximum
iterations, and the total iterations within a fixed duration. Variants of
benchmark are run with 1, 2, 3, 4, nproc/4, nproc/2, nproc threads.

The size of critical section is determined by the number of times of pause
(x86 only) and read which is intended to emulate the scenarios in real
applications. In this microbenchmark, the number 1, 10, 100, and 1000 are
used to represent different size of critical sections in the working set.

    * benchtests/bench-mutex-adaptive-thread.c: Microbenchmark for
    adaptive spin mutex
    * benchmark/Makefile: Add adaptive spin mutex benchmark

ChangLog:
    V2->V3:
    a) Add some delay after mutex unlock to reduce the possibility of lock
    acquisition by the previous lock holder, and that makes more sense
    for practical applications
    b) Sync threads to start simultaneously
    c) Set CPU affinity for threads

    V1->V2:
    New added microbenchmark, as requested by Adhemerval Zanella

Signed-off-by: Kemi Wang <kemi.wang@intel.com>
---
 ChangeLog                                |   6 +
 benchtests/Makefile                      |  36 ++++-
 benchtests/bench-mutex-adaptive-thread.c | 251 +++++++++++++++++++++++++++++++
 3 files changed, 286 insertions(+), 7 deletions(-)
 create mode 100644 benchtests/bench-mutex-adaptive-thread.c

diff --git a/ChangeLog b/ChangeLog
index c1e2a44..e2991e9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2018-05-23  Kemi Wang <kemi.wang@intel.com>
 
+	* benchtests/bench-mutex-adaptive-thread.c: Microbenchmark for adaptive
+	spin mutex.
+	* benchmark/Makefile: Add adaptive spin mutex benchmark.
+
+2018-05-23  Kemi Wang <kemi.wang@intel.com>
+
 	* elf/dl-tunables.list: Add glibc.mutex.spin_count entry.
 	* manual/tunables.texi: Add glibc.mutex.spin_count description.
 	* nptl/Makefile: Add pthread_mutex_conf.c for compilation.
diff --git a/benchtests/Makefile b/benchtests/Makefile
index bcd6a9c..fcc768f 100644
--- a/benchtests/Makefile
+++ b/benchtests/Makefile
@@ -95,10 +95,17 @@ else
 bench-malloc := $(filter malloc-%,${BENCHSET})
 endif
 
+ifeq (${BENCHSET},)
+bench-mutex := mutex-adaptive-thread
+else
+bench-mutex := $(filter mutex-%,${BENCHSET})
+endif
+
 $(addprefix $(objpfx)bench-,$(bench-math)): $(libm)
 $(addprefix $(objpfx)bench-,$(math-benchset)): $(libm)
 $(addprefix $(objpfx)bench-,$(bench-pthread)): $(shared-thread-library)
 $(objpfx)bench-malloc-thread: $(shared-thread-library)
+$(addprefix $(objpfx)bench-,$(bench-mutex)): $(shared-thread-library)
 
 
 
@@ -119,6 +126,7 @@ include ../Rules
 binaries-bench := $(addprefix $(objpfx)bench-,$(bench))
 binaries-benchset := $(addprefix $(objpfx)bench-,$(benchset))
 binaries-bench-malloc := $(addprefix $(objpfx)bench-,$(bench-malloc))
+binaries-bench-mutex := $(addprefix $(objpfx)bench-,$(bench-mutex))
 
 # The default duration: 10 seconds.
 ifndef BENCH_DURATION
@@ -142,7 +150,7 @@ endif
 # This makes sure CPPFLAGS-nonlib and CFLAGS-nonlib are passed
 # for all these modules.
 cpp-srcs-left := $(binaries-benchset:=.c) $(binaries-bench:=.c) \
-		 $(binaries-bench-malloc:=.c)
+	$(binaries-bench-malloc:=.c) $(binaries-bench-mutex:=.c)
 lib := nonlib
 include $(patsubst %,$(..)libof-iterator.mk,$(cpp-srcs-left))
 
@@ -158,6 +166,7 @@ bench-clean:
 	rm -f $(binaries-bench) $(addsuffix .o,$(binaries-bench))
 	rm -f $(binaries-benchset) $(addsuffix .o,$(binaries-benchset))
 	rm -f $(binaries-bench-malloc) $(addsuffix .o,$(binaries-bench-malloc))
+	rm -f $(binaries-bench-mutex) $(addsuffix .o,$(binaries-bench-mutex))
 	rm -f $(timing-type) $(addsuffix .o,$(timing-type))
 	rm -f $(addprefix $(objpfx),$(bench-extra-objs))
 
@@ -165,7 +174,7 @@ bench-clean:
 ifneq ($(strip ${BENCHSET}),)
 VALIDBENCHSETNAMES := bench-pthread bench-math bench-string string-benchset \
    wcsmbs-benchset stdlib-benchset stdio-common-benchset math-benchset \
-   malloc-thread
+   malloc-thread mutex-adaptive-thread
 INVALIDBENCHSETNAMES := $(filter-out ${VALIDBENCHSETNAMES},${BENCHSET})
 ifneq (${INVALIDBENCHSETNAMES},)
 $(info The following values in BENCHSET are invalid: ${INVALIDBENCHSETNAMES})
@@ -176,7 +185,7 @@ endif
 
 # Define the bench target only if the target has a usable python installation.
 ifdef PYTHON
-bench: bench-build bench-set bench-func bench-malloc
+bench: bench-build bench-set bench-func bench-malloc bench-mutex
 else
 bench:
 	@echo "The bench target needs python to run."
@@ -187,10 +196,10 @@ endif
 # only if we're building natively.
 ifeq (no,$(cross-compiling))
 bench-build: $(gen-locales) $(timing-type) $(binaries-bench) \
-	$(binaries-benchset) $(binaries-bench-malloc)
+	$(binaries-benchset) $(binaries-bench-malloc) $(binaries-bench-mutex)
 else
 bench-build: $(timing-type) $(binaries-bench) $(binaries-benchset) \
-	$(binaries-bench-malloc)
+	$(binaries-bench-malloc) $(binaries-bench-mutex)
 endif
 
 bench-set: $(binaries-benchset)
@@ -207,6 +216,19 @@ bench-malloc: $(binaries-bench-malloc)
 	  done;\
 	done
 
+# Run benchmark with 1, 2, 3, nproc/2, nproc threads
+bench-mutex: $(binaries-bench-mutex)
+	for run in $^; do \
+		prev=0; \
+		for thr in 1 2 3 4 $$((`nproc` / 4)) $$((`nproc` / 2)) `nproc`; do \
+			if [ $$thr -gt $$prev -a $$thr -lt `nproc` ]; then \
+			echo "Running $${run} $${thr}"; \
+			fi; \
+			prev=$$thr; \
+	  $(run-bench) $${thr} > $${run}-$${thr}.out; \
+	  done;\
+	done
+
 # Build and execute the benchmark functions.  This target generates JSON
 # formatted bench.out.  Each of the programs produce independent JSON output,
 # so one could even execute them individually and process it using any JSON
@@ -236,8 +258,8 @@ bench-func: $(binaries-bench)
 	fi
 
 $(timing-type) $(binaries-bench) $(binaries-benchset) \
-	$(binaries-bench-malloc): %: %.o $(objpfx)json-lib.o \
-	$(link-extra-libs-tests) \
+	$(binaries-bench-malloc) $(binaries-bench-mutex): \
+	%: %.o $(objpfx)json-lib.o $(link-extra-libs-tests) \
   $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
   $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
 	$(+link-tests)
diff --git a/benchtests/bench-mutex-adaptive-thread.c b/benchtests/bench-mutex-adaptive-thread.c
new file mode 100644
index 0000000..ce9c40e
--- /dev/null
+++ b/benchtests/bench-mutex-adaptive-thread.c
@@ -0,0 +1,251 @@
+/* Benchmark pthread adaptive spin mutex lock and unlock functions.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <sched.h>
+
+#include "bench-timing.h"
+#include "json-lib.h"
+
+/* Benchmark duration in seconds.  */
+#define BENCHMARK_DURATION	15
+#define TYPE PTHREAD_MUTEX_ADAPTIVE_NP
+#define mb() asm ("" ::: "memory")
+#define UNLOCK_DELAY 10
+
+#if defined (__i386__) || defined (__x86_64__)
+# define cpu_relax() asm ("rep; nop")
+#else
+# define cpu_relax() do { } while (0)
+#endif
+
+static volatile int start_thread;
+static unsigned long long val;
+static pthread_mutexattr_t attr;
+static pthread_mutex_t mutex;
+
+#define WORKING_SET_SIZE  4
+int working_set[] = {1, 10, 100, 1000};
+
+struct thread_args
+{
+  unsigned long long iters;
+  int working_set;
+  timing_t elapsed;
+};
+
+static void
+init_mutex (void)
+{
+  pthread_mutexattr_init (&attr);
+  pthread_mutexattr_settype (&attr, TYPE);
+  pthread_mutex_init (&mutex, &attr);
+}
+
+static void
+init_parameter (int size, struct thread_args *args, int num_thread)
+{
+  int i;
+  for (i = 0; i < num_thread; i++)
+    {
+      memset(&args[i], 0, sizeof(struct thread_args));
+      args[i].working_set = size;
+    }
+}
+
+static volatile bool timeout;
+
+static void
+alarm_handler (int signum)
+{
+  timeout = true;
+}
+
+static inline void
+delay (int number)
+{
+  while (number > 0)
+  {
+    cpu_relax ();
+    number--;
+  }
+}
+
+/* Lock and unlock for protecting the critical section.  */
+static unsigned long long
+mutex_benchmark_loop (int number)
+{
+  unsigned long long iters = 0;
+
+  while (!start_thread)
+   cpu_relax ();
+
+  while (!timeout)
+    {
+      pthread_mutex_lock (&mutex);
+      val++;
+      delay (number);
+      pthread_mutex_unlock (&mutex);
+      iters++;
+      delay (UNLOCK_DELAY);
+    }
+  return iters;
+}
+
+static void *
+benchmark_thread (void *arg)
+{
+  struct thread_args *args = (struct thread_args *) arg;
+  unsigned long long iters;
+  timing_t start, stop;
+
+  TIMING_NOW (start);
+  iters = mutex_benchmark_loop (args->working_set);
+  TIMING_NOW (stop);
+
+  TIMING_DIFF (args->elapsed, start, stop);
+  args->iters = iters;
+
+  return NULL;
+}
+
+static void
+do_benchmark (size_t num_thread, struct thread_args *args)
+{
+
+  pthread_t threads[num_thread];
+
+  for (size_t i = 0; i < num_thread; i++)
+    {
+      pthread_attr_t attr;
+      cpu_set_t set;
+
+      pthread_attr_init (&attr);
+      CPU_ZERO (&set);
+      CPU_SET (i, &set);
+      pthread_attr_setaffinity_np (&attr, sizeof(cpu_set_t), &set);
+      pthread_create (&threads[i], &attr, benchmark_thread, args + i);
+      pthread_attr_destroy (&attr);
+    }
+
+  mb ();
+  start_thread = 1;
+  mb ();
+  sched_yield ();
+  for (size_t i = 0; i < num_thread; i++)
+    pthread_join(threads[i], NULL);
+}
+
+static void
+usage(const char *name)
+{
+  fprintf (stderr, "%s: <num_thread>\n", name);
+  exit (1);
+}
+
+int
+main (int argc, char **argv)
+{
+  int i, j, num_thread = 1;
+  json_ctx_t json_ctx;
+  struct sigaction act;
+
+  if (argc == 1)
+    num_thread = 1;
+  else if (argc == 2)
+    {
+      long ret;
+
+      errno = 0;
+      ret = strtol(argv[1], NULL, 10);
+
+      if (errno || ret == 0)
+	    usage(argv[0]);
+
+      num_thread = ret;
+    }
+  else
+    usage(argv[0]);
+
+  /* Benchmark for different critical section size.  */
+  for (i = 0; i < WORKING_SET_SIZE; i++)
+    {
+      int size = working_set[i];
+      struct thread_args args[num_thread];
+      unsigned long long iters = 0, min_iters = -1ULL, max_iters = 0;
+      double d_total_s = 0, d_total_i = 0;
+
+      timeout = false;
+      init_mutex ();
+      init_parameter (size, args, num_thread);
+
+      json_init (&json_ctx, 0, stdout);
+
+      json_document_begin (&json_ctx);
+
+      json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
+
+      json_attr_object_begin (&json_ctx, "functions");
+
+      json_attr_object_begin (&json_ctx, "mutex");
+
+      json_attr_object_begin (&json_ctx, "");
+
+      memset (&act, 0, sizeof (act));
+      act.sa_handler = &alarm_handler;
+
+      sigaction (SIGALRM, &act, NULL);
+
+      alarm (BENCHMARK_DURATION);
+
+      do_benchmark (num_thread, args);
+
+      for (j = 0; j < num_thread; j++)
+        {
+          iters = args[j].iters;
+          if (iters < min_iters)
+            min_iters = iters;
+          if (iters >= max_iters)
+            max_iters = iters;
+          d_total_i += iters;
+          TIMING_ACCUM (d_total_s, args[j].elapsed);
+        }
+      json_attr_double (&json_ctx, "duration", d_total_s);
+      json_attr_double (&json_ctx, "total_iterations", d_total_i);
+      json_attr_double (&json_ctx, "min_iteration", min_iters);
+      json_attr_double (&json_ctx, "max_iteration", max_iters);
+      json_attr_double (&json_ctx, "time_per_iteration", d_total_s / d_total_i);
+      json_attr_double (&json_ctx, "threads", num_thread);
+      json_attr_double (&json_ctx, "critical_section_size", size);
+
+      json_attr_object_end (&json_ctx);
+      json_attr_object_end (&json_ctx);
+      json_attr_object_end (&json_ctx);
+
+      json_document_end (&json_ctx);
+      fputs("\n", (&json_ctx)->fp);
+    }
+  return 0;
+}
-- 
2.7.4