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![Vincent Whitchurch](/assets/img/avatar_default.png)
For memcpy, the source pages are memset to zero only when --cycles is
used. This leads to wildly different results with or without --cycles,
since all sources pages are likely to be mapped to the same zero page
without explicit writes.
Before this fix:
$ export cmd="./perf stat -e LLC-loads -- ./perf bench \
mem memcpy -s 1024MB -l 100 -f default"
$ $cmd
2,935,826 LLC-loads
3.821677452 seconds time elapsed
$ $cmd --cycles
217,533,436 LLC-loads
8.616725985 seconds time elapsed
After this fix:
$ $cmd
214,459,686 LLC-loads
8.674301124 seconds time elapsed
$ $cmd --cycles
214,758,651 LLC-loads
8.644480006 seconds time elapsed
Fixes: 47b5757bac
("perf bench mem: Move boilerplate memory allocation to the infrastructure")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel@axis.com
Link: http://lore.kernel.org/lkml/20200810133404.30829-1-vincent.whitchurch@axis.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
375 lines
8.7 KiB
C
375 lines
8.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* mem-memcpy.c
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*
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* Simple memcpy() and memset() benchmarks
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*
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* Written by Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
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*/
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#include "debug.h"
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#include "../perf-sys.h"
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#include <subcmd/parse-options.h>
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#include "../util/header.h"
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#include "../util/cloexec.h"
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#include "../util/string2.h"
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#include "bench.h"
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#include "mem-memcpy-arch.h"
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#include "mem-memset-arch.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/time.h>
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#include <errno.h>
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#include <linux/time64.h>
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#include <linux/zalloc.h>
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#define K 1024
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static const char *size_str = "1MB";
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static const char *function_str = "all";
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static int nr_loops = 1;
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static bool use_cycles;
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static int cycles_fd;
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static const struct option options[] = {
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OPT_STRING('s', "size", &size_str, "1MB",
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"Specify the size of the memory buffers. "
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"Available units: B, KB, MB, GB and TB (case insensitive)"),
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OPT_STRING('f', "function", &function_str, "all",
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"Specify the function to run, \"all\" runs all available functions, \"help\" lists them"),
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OPT_INTEGER('l', "nr_loops", &nr_loops,
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"Specify the number of loops to run. (default: 1)"),
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OPT_BOOLEAN('c', "cycles", &use_cycles,
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"Use a cycles event instead of gettimeofday() to measure performance"),
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OPT_END()
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};
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typedef void *(*memcpy_t)(void *, const void *, size_t);
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typedef void *(*memset_t)(void *, int, size_t);
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struct function {
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const char *name;
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const char *desc;
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union {
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memcpy_t memcpy;
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memset_t memset;
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} fn;
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};
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static struct perf_event_attr cycle_attr = {
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.type = PERF_TYPE_HARDWARE,
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.config = PERF_COUNT_HW_CPU_CYCLES
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};
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static int init_cycles(void)
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{
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cycles_fd = sys_perf_event_open(&cycle_attr, getpid(), -1, -1, perf_event_open_cloexec_flag());
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if (cycles_fd < 0 && errno == ENOSYS) {
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pr_debug("No CONFIG_PERF_EVENTS=y kernel support configured?\n");
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return -1;
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}
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return cycles_fd;
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}
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static u64 get_cycles(void)
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{
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int ret;
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u64 clk;
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ret = read(cycles_fd, &clk, sizeof(u64));
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BUG_ON(ret != sizeof(u64));
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return clk;
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}
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static double timeval2double(struct timeval *ts)
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{
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return (double)ts->tv_sec + (double)ts->tv_usec / (double)USEC_PER_SEC;
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}
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#define print_bps(x) do { \
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if (x < K) \
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printf(" %14lf bytes/sec\n", x); \
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else if (x < K * K) \
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printf(" %14lfd KB/sec\n", x / K); \
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else if (x < K * K * K) \
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printf(" %14lf MB/sec\n", x / K / K); \
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else \
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printf(" %14lf GB/sec\n", x / K / K / K); \
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} while (0)
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struct bench_mem_info {
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const struct function *functions;
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u64 (*do_cycles)(const struct function *r, size_t size, void *src, void *dst);
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double (*do_gettimeofday)(const struct function *r, size_t size, void *src, void *dst);
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const char *const *usage;
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bool alloc_src;
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};
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static void __bench_mem_function(struct bench_mem_info *info, int r_idx, size_t size, double size_total)
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{
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const struct function *r = &info->functions[r_idx];
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double result_bps = 0.0;
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u64 result_cycles = 0;
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void *src = NULL, *dst = zalloc(size);
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printf("# function '%s' (%s)\n", r->name, r->desc);
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if (dst == NULL)
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goto out_alloc_failed;
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if (info->alloc_src) {
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src = zalloc(size);
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if (src == NULL)
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goto out_alloc_failed;
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}
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if (bench_format == BENCH_FORMAT_DEFAULT)
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printf("# Copying %s bytes ...\n\n", size_str);
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if (use_cycles) {
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result_cycles = info->do_cycles(r, size, src, dst);
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} else {
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result_bps = info->do_gettimeofday(r, size, src, dst);
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}
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switch (bench_format) {
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case BENCH_FORMAT_DEFAULT:
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if (use_cycles) {
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printf(" %14lf cycles/byte\n", (double)result_cycles/size_total);
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} else {
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print_bps(result_bps);
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}
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break;
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case BENCH_FORMAT_SIMPLE:
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if (use_cycles) {
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printf("%lf\n", (double)result_cycles/size_total);
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} else {
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printf("%lf\n", result_bps);
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}
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break;
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default:
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BUG_ON(1);
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break;
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}
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out_free:
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free(src);
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free(dst);
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return;
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out_alloc_failed:
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printf("# Memory allocation failed - maybe size (%s) is too large?\n", size_str);
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goto out_free;
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}
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static int bench_mem_common(int argc, const char **argv, struct bench_mem_info *info)
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{
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int i;
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size_t size;
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double size_total;
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argc = parse_options(argc, argv, options, info->usage, 0);
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if (use_cycles) {
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i = init_cycles();
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if (i < 0) {
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fprintf(stderr, "Failed to open cycles counter\n");
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return i;
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}
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}
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size = (size_t)perf_atoll((char *)size_str);
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size_total = (double)size * nr_loops;
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if ((s64)size <= 0) {
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fprintf(stderr, "Invalid size:%s\n", size_str);
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return 1;
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}
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if (!strncmp(function_str, "all", 3)) {
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for (i = 0; info->functions[i].name; i++)
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__bench_mem_function(info, i, size, size_total);
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return 0;
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}
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for (i = 0; info->functions[i].name; i++) {
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if (!strcmp(info->functions[i].name, function_str))
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break;
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}
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if (!info->functions[i].name) {
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if (strcmp(function_str, "help") && strcmp(function_str, "h"))
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printf("Unknown function: %s\n", function_str);
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printf("Available functions:\n");
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for (i = 0; info->functions[i].name; i++) {
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printf("\t%s ... %s\n",
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info->functions[i].name, info->functions[i].desc);
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}
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return 1;
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}
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__bench_mem_function(info, i, size, size_total);
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return 0;
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}
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static void memcpy_prefault(memcpy_t fn, size_t size, void *src, void *dst)
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{
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/* Make sure to always prefault zero pages even if MMAP_THRESH is crossed: */
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memset(src, 0, size);
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/*
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* We prefault the freshly allocated memory range here,
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* to not measure page fault overhead:
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*/
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fn(dst, src, size);
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}
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static u64 do_memcpy_cycles(const struct function *r, size_t size, void *src, void *dst)
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{
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u64 cycle_start = 0ULL, cycle_end = 0ULL;
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memcpy_t fn = r->fn.memcpy;
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int i;
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memcpy_prefault(fn, size, src, dst);
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cycle_start = get_cycles();
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for (i = 0; i < nr_loops; ++i)
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fn(dst, src, size);
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cycle_end = get_cycles();
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return cycle_end - cycle_start;
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}
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static double do_memcpy_gettimeofday(const struct function *r, size_t size, void *src, void *dst)
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{
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struct timeval tv_start, tv_end, tv_diff;
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memcpy_t fn = r->fn.memcpy;
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int i;
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memcpy_prefault(fn, size, src, dst);
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BUG_ON(gettimeofday(&tv_start, NULL));
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for (i = 0; i < nr_loops; ++i)
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fn(dst, src, size);
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BUG_ON(gettimeofday(&tv_end, NULL));
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timersub(&tv_end, &tv_start, &tv_diff);
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return (double)(((double)size * nr_loops) / timeval2double(&tv_diff));
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}
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struct function memcpy_functions[] = {
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{ .name = "default",
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.desc = "Default memcpy() provided by glibc",
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.fn.memcpy = memcpy },
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#ifdef HAVE_ARCH_X86_64_SUPPORT
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# define MEMCPY_FN(_fn, _name, _desc) {.name = _name, .desc = _desc, .fn.memcpy = _fn},
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# include "mem-memcpy-x86-64-asm-def.h"
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# undef MEMCPY_FN
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#endif
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{ .name = NULL, }
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};
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static const char * const bench_mem_memcpy_usage[] = {
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"perf bench mem memcpy <options>",
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NULL
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};
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int bench_mem_memcpy(int argc, const char **argv)
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{
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struct bench_mem_info info = {
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.functions = memcpy_functions,
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.do_cycles = do_memcpy_cycles,
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.do_gettimeofday = do_memcpy_gettimeofday,
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.usage = bench_mem_memcpy_usage,
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.alloc_src = true,
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};
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return bench_mem_common(argc, argv, &info);
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}
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static u64 do_memset_cycles(const struct function *r, size_t size, void *src __maybe_unused, void *dst)
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{
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u64 cycle_start = 0ULL, cycle_end = 0ULL;
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memset_t fn = r->fn.memset;
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int i;
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/*
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* We prefault the freshly allocated memory range here,
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* to not measure page fault overhead:
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*/
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fn(dst, -1, size);
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cycle_start = get_cycles();
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for (i = 0; i < nr_loops; ++i)
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fn(dst, i, size);
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cycle_end = get_cycles();
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return cycle_end - cycle_start;
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}
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static double do_memset_gettimeofday(const struct function *r, size_t size, void *src __maybe_unused, void *dst)
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{
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struct timeval tv_start, tv_end, tv_diff;
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memset_t fn = r->fn.memset;
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int i;
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/*
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* We prefault the freshly allocated memory range here,
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* to not measure page fault overhead:
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*/
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fn(dst, -1, size);
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BUG_ON(gettimeofday(&tv_start, NULL));
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for (i = 0; i < nr_loops; ++i)
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fn(dst, i, size);
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BUG_ON(gettimeofday(&tv_end, NULL));
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timersub(&tv_end, &tv_start, &tv_diff);
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return (double)(((double)size * nr_loops) / timeval2double(&tv_diff));
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}
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static const char * const bench_mem_memset_usage[] = {
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"perf bench mem memset <options>",
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NULL
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};
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static const struct function memset_functions[] = {
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{ .name = "default",
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.desc = "Default memset() provided by glibc",
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.fn.memset = memset },
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#ifdef HAVE_ARCH_X86_64_SUPPORT
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# define MEMSET_FN(_fn, _name, _desc) { .name = _name, .desc = _desc, .fn.memset = _fn },
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# include "mem-memset-x86-64-asm-def.h"
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# undef MEMSET_FN
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#endif
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{ .name = NULL, }
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};
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int bench_mem_memset(int argc, const char **argv)
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{
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struct bench_mem_info info = {
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.functions = memset_functions,
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.do_cycles = do_memset_cycles,
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.do_gettimeofday = do_memset_gettimeofday,
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.usage = bench_mem_memset_usage,
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};
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return bench_mem_common(argc, argv, &info);
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}
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