Add two mmap() workloads: one that eagerly populates a region and
another that demand faults it in.

The intent is to probe the memory subsytem performance incurred
by mmap().

  $ perf bench mem mmap -s 4gb -p 4kb -l 10 -f populate
  # Running 'mem/mmap' benchmark:
  # function 'populate' (Eagerly populated map())
  # Copying 4gb bytes ...

       1.811691 GB/sec

  $ perf bench mem mmap -s 4gb -p 2mb -l 10 -f populate
  # Running 'mem/mmap' benchmark:
  # function 'populate' (Eagerly populated mmap())
  # Copying 4gb bytes ...

      12.272017 GB/sec

  $ perf bench mem mmap -s 4gb -p 1gb -l 10 -f populate
  # Running 'mem/mmap' benchmark:
  # function 'populate' (Eagerly populated mmap())
  # Copying 4gb bytes ...

      17.085927 GB/sec

Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---
 tools/perf/Documentation/perf-bench.txt | 34 +++++++++
 tools/perf/bench/bench.h                |  1 +
 tools/perf/bench/mem-functions.c        | 96 +++++++++++++++++++++++++
 tools/perf/builtin-bench.c              |  1 +
 4 files changed, 132 insertions(+)

diff --git a/tools/perf/Documentation/perf-bench.txt b/tools/perf/Documentation/perf-bench.txt
index 3d1455d880c3..1160224cb718 100644
--- a/tools/perf/Documentation/perf-bench.txt
+++ b/tools/perf/Documentation/perf-bench.txt
@@ -240,6 +240,40 @@ Repeat memset invocation this number of times.
 --cycles::
 Use perf's cpu-cycles event instead of gettimeofday syscall.
 
+*mmap*::
+Suite for evaluating memory subsystem performance for mmap()'d memory.
+
+Options of *mmap*
+^^^^^^^^^^^^^^^^^
+-s::
+--size::
+Specify size of memory to set (default: 1MB).
+Available units are B, KB, MB, GB and TB (case insensitive).
+
+-p::
+--page::
+Specify page-size for mapping memory buffers (default: 4KB).
+Available values are 4KB, 2MB, 1GB (case insensitive).
+
+-r::
+--randomize::
+Specify seed to randomize page access offset (default: 0, or not randomized).
+
+-f::
+--function::
+Specify function to set (default: all).
+Available functions are 'demand' and 'populate', with the first
+demand faulting pages in the region and the second using an eager
+mapping.
+
+-l::
+--nr_loops::
+Repeat mmap() invocation this number of times.
+
+-c::
+--cycles::
+Use perf's cpu-cycles event instead of gettimeofday syscall.
+
 SUITES FOR 'numa'
 ~~~~~~~~~~~~~~~~~
 *mem*::
diff --git a/tools/perf/bench/bench.h b/tools/perf/bench/bench.h
index 9f736423af53..8519eb5a42fa 100644
--- a/tools/perf/bench/bench.h
+++ b/tools/perf/bench/bench.h
@@ -28,6 +28,7 @@ int bench_syscall_fork(int argc, const char **argv);
 int bench_syscall_execve(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_mem_mmap(int argc, const char **argv);
 int bench_mem_find_bit(int argc, const char **argv);
 int bench_futex_hash(int argc, const char **argv);
 int bench_futex_wake(int argc, const char **argv);
diff --git a/tools/perf/bench/mem-functions.c b/tools/perf/bench/mem-functions.c
index 2a23bed8c2d3..2908a3a796c9 100644
--- a/tools/perf/bench/mem-functions.c
+++ b/tools/perf/bench/mem-functions.c
@@ -40,6 +40,7 @@ static const char	*chunk_size_str	= "0";
 static unsigned int	nr_loops	= 1;
 static bool		use_cycles;
 static int		cycles_fd;
+static unsigned int	seed;
 
 static const struct option bench_common_options[] = {
 	OPT_STRING('s', "size", &size_str, "1MB",
@@ -81,6 +82,7 @@ struct bench_params {
 	size_t		chunk_size;
 	unsigned int	nr_loops;
 	unsigned int	page_shift;
+	unsigned int	seed;
 };
 
 struct bench_mem_info {
@@ -98,6 +100,7 @@ typedef void (*mem_fini_t)(struct bench_mem_info *, struct bench_params *,
 			   void **, void **);
 typedef void *(*memcpy_t)(void *, const void *, size_t);
 typedef void *(*memset_t)(void *, int, size_t);
+typedef void (*mmap_op_t)(void *, size_t, unsigned int, bool);
 
 struct function {
 	const char *name;
@@ -108,6 +111,7 @@ struct function {
 		union {
 			memcpy_t memcpy;
 			memset_t memset;
+			mmap_op_t mmap_op;
 		};
 	} fn;
 };
@@ -160,6 +164,14 @@ static union bench_clock clock_diff(union bench_clock *s, union bench_clock *e)
 	return t;
 }
 
+static void clock_accum(union bench_clock *a, union bench_clock *b)
+{
+	if (use_cycles)
+		a->cycles += b->cycles;
+	else
+		timeradd(&a->tv, &b->tv, &a->tv);
+}
+
 static double timeval2double(struct timeval *ts)
 {
 	return (double)ts->tv_sec + (double)ts->tv_usec / (double)USEC_PER_SEC;
@@ -271,6 +283,8 @@ static int bench_mem_common(int argc, const char **argv, struct bench_mem_info *
 	}
 	p.page_shift = ilog2(page_size);
 
+	p.seed = seed;
+
 	if (!strncmp(function_str, "all", 3)) {
 		for (i = 0; info->functions[i].name; i++)
 			__bench_mem_function(info, &p, i);
@@ -465,3 +479,85 @@ int bench_mem_memset(int argc, const char **argv)
 
 	return bench_mem_common(argc, argv, &info);
 }
+
+static void mmap_page_touch(void *dst, size_t size, unsigned int page_shift, bool random)
+{
+	unsigned long npages = size / (1 << page_shift);
+	unsigned long offset = 0, r = 0;
+
+	for (unsigned long i = 0; i < npages; i++) {
+		if (random)
+			r = rand() % (1 << page_shift);
+
+		*((char *)dst + offset + r) = *(char *)(dst + offset + r) + i;
+		offset += 1 << page_shift;
+	}
+}
+
+static int do_mmap(const struct function *r, struct bench_params *p,
+		  void *src __maybe_unused, void *dst __maybe_unused,
+		  union bench_clock *accum)
+{
+	union bench_clock start, end, diff;
+	mmap_op_t fn = r->fn.mmap_op;
+	bool populate = strcmp(r->name, "populate") == 0;
+
+	if (p->seed)
+		srand(p->seed);
+
+	for (unsigned int i = 0; i < p->nr_loops; i++) {
+		clock_get(&start);
+		dst = bench_mmap(p->size, populate, p->page_shift);
+		if (!dst)
+			goto out;
+
+		fn(dst, p->size, p->page_shift, p->seed);
+		clock_get(&end);
+		diff = clock_diff(&start, &end);
+		clock_accum(accum, &diff);
+
+		bench_munmap(dst, p->size);
+	}
+
+	return 0;
+out:
+	printf("# Memory allocation failed - maybe size (%s) %s?\n", size_str,
+			p->page_shift != PAGE_SHIFT_4KB ? "has insufficient hugepages" : "is too large");
+	return -1;
+}
+
+static const char * const bench_mem_mmap_usage[] = {
+	"perf bench mem mmap <options>",
+	NULL
+};
+
+static const struct function mmap_functions[] = {
+	{ .name		= "demand",
+	  .desc		= "Demand loaded mmap()",
+	  .fn.mmap_op	= mmap_page_touch },
+
+	{ .name		= "populate",
+	  .desc		= "Eagerly populated mmap()",
+	  .fn.mmap_op	= mmap_page_touch },
+
+	{ .name = NULL, }
+};
+
+int bench_mem_mmap(int argc, const char **argv)
+{
+	static const struct option bench_mmap_options[] = {
+		OPT_UINTEGER('r', "randomize", &seed,
+			    "Seed to randomize page access offset."),
+		OPT_PARENT(bench_common_options),
+		OPT_END()
+	};
+
+	struct bench_mem_info info = {
+		.functions		= mmap_functions,
+		.do_op			= do_mmap,
+		.usage			= bench_mem_mmap_usage,
+		.options		= bench_mmap_options,
+	};
+
+	return bench_mem_common(argc, argv, &info);
+}
diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c
index 2c1a9f3d847a..02dea1b88228 100644
--- a/tools/perf/builtin-bench.c
+++ b/tools/perf/builtin-bench.c
@@ -65,6 +65,7 @@ static struct bench mem_benchmarks[] = {
 	{ "memcpy",	"Benchmark for memcpy() functions",		bench_mem_memcpy	},
 	{ "memset",	"Benchmark for memset() functions",		bench_mem_memset	},
 	{ "find_bit",	"Benchmark for find_bit() functions",		bench_mem_find_bit	},
+	{ "mmap",	"Benchmark for mmap() mappings",		bench_mem_mmap		},
 	{ "all",	"Run all memory access benchmarks",		NULL			},
 	{ NULL,		NULL,						NULL			}
 };
-- 
2.31.1