1 | /* Measure memcpy function combined throughput for different alignments. |
2 | Copyright (C) 2017-2022 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | /* This microbenchmark measures the throughput of memcpy for various sizes from |
20 | 1 byte to 32MiB, doubling every iteration and then misaligning by 0-15 |
21 | bytes. The copies are done from source to destination and then back and the |
22 | source walks forward across the array and the destination walks backward by |
23 | one byte each, thus measuring misaligned accesses as well. The idea is to |
24 | avoid caching effects by copying a different string and far enough from each |
25 | other, walking in different directions so that we can measure prefetcher |
26 | efficiency (software or hardware) more closely than with a loop copying the |
27 | same data over and over, which eventually only gives us L1 cache |
28 | performance. */ |
29 | |
30 | #ifndef MEMCPY_RESULT |
31 | # define MEMCPY_RESULT(dst, len) dst |
32 | # define START_SIZE 128 |
33 | # define MIN_PAGE_SIZE (getpagesize () + 32 * 1024 * 1024) |
34 | # define TEST_MAIN |
35 | # define TEST_NAME "memcpy" |
36 | # define TIMEOUT (20 * 60) |
37 | # include "bench-string.h" |
38 | |
39 | IMPL (memcpy, 1) |
40 | #endif |
41 | |
42 | #include "json-lib.h" |
43 | |
44 | typedef char *(*proto_t) (char *, const char *, size_t); |
45 | |
46 | static void |
47 | do_one_test (json_ctx_t *json_ctx, impl_t *impl, char *dst, char *src, |
48 | size_t len) |
49 | { |
50 | size_t i = 0; |
51 | timing_t start, stop, cur; |
52 | |
53 | char *dst_end = dst + MIN_PAGE_SIZE - len; |
54 | char *src_end = src + MIN_PAGE_SIZE - len; |
55 | |
56 | TIMING_NOW (start); |
57 | /* Copy the entire buffer backwards, LEN at a time. */ |
58 | for (; src_end >= src && dst_end >= dst; src_end -= len, dst_end -= len, i++) |
59 | CALL (impl, src_end, dst_end, len); |
60 | TIMING_NOW (stop); |
61 | |
62 | TIMING_DIFF (cur, start, stop); |
63 | |
64 | /* Get time taken per function call. */ |
65 | json_element_double (ctx: json_ctx, d: (double) cur / i); |
66 | } |
67 | |
68 | static void |
69 | do_test (json_ctx_t *json_ctx, size_t len, int both_ways) |
70 | { |
71 | |
72 | char *s1, *s2; |
73 | size_t repeats; |
74 | s1 = (char *) (buf1); |
75 | s2 = (char *) (buf2); |
76 | |
77 | for (repeats = both_ways ? 2 : 1; repeats; --repeats) |
78 | { |
79 | json_element_object_begin (ctx: json_ctx); |
80 | json_attr_uint (ctx: json_ctx, name: "length" , d: (double) len); |
81 | json_attr_uint (ctx: json_ctx, name: "dst > src" , d: (double) (s2 > s1)); |
82 | json_array_begin (ctx: json_ctx, name: "timings" ); |
83 | |
84 | FOR_EACH_IMPL (impl, 0) |
85 | do_one_test (json_ctx, impl, dst: s2, src: s1, len); |
86 | |
87 | json_array_end (ctx: json_ctx); |
88 | json_element_object_end (ctx: json_ctx); |
89 | |
90 | s1 = (char *) (buf2); |
91 | s2 = (char *) (buf1); |
92 | } |
93 | } |
94 | |
95 | int |
96 | test_main (void) |
97 | { |
98 | json_ctx_t json_ctx; |
99 | |
100 | test_init (); |
101 | |
102 | json_init (ctx: &json_ctx, indent_level: 0, stdout); |
103 | |
104 | json_document_begin (ctx: &json_ctx); |
105 | json_attr_string (ctx: &json_ctx, name: "timing_type" , TIMING_TYPE); |
106 | |
107 | json_attr_object_begin (ctx: &json_ctx, name: "functions" ); |
108 | json_attr_object_begin (ctx: &json_ctx, name: "memcpy" ); |
109 | json_attr_string (ctx: &json_ctx, name: "bench-variant" , s: "walk" ); |
110 | |
111 | json_array_begin (ctx: &json_ctx, name: "ifuncs" ); |
112 | FOR_EACH_IMPL (impl, 0) |
113 | json_element_string (ctx: &json_ctx, s: impl->name); |
114 | json_array_end (ctx: &json_ctx); |
115 | |
116 | json_array_begin (ctx: &json_ctx, name: "results" ); |
117 | for (size_t i = START_SIZE; i <= MIN_PAGE_SIZE; i <<= 1) |
118 | { |
119 | do_test (json_ctx: &json_ctx, len: i, both_ways: 1); |
120 | do_test (json_ctx: &json_ctx, len: i + 1, both_ways: 1); |
121 | } |
122 | |
123 | json_array_end (ctx: &json_ctx); |
124 | json_attr_object_end (ctx: &json_ctx); |
125 | json_attr_object_end (ctx: &json_ctx); |
126 | json_document_end (ctx: &json_ctx); |
127 | |
128 | return ret; |
129 | } |
130 | |
131 | #include <support/test-driver.c> |
132 | |