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fc335a0ded
This patch adds support for testing memcpy with both dst > src and dst < src. Since memcpy is implemented as memmove which has seperate control flows for certain sizes depending on dst > src it seems like 1) information that should be provided in the benchtest output and a variable that can be controlled for the benchmarks. Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
132 lines
4.0 KiB
C
132 lines
4.0 KiB
C
/* Measure memcpy function combined throughput for different alignments.
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Copyright (C) 2017-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* This microbenchmark measures the throughput of memcpy for various sizes from
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1 byte to 32MiB, doubling every iteration and then misaligning by 0-15
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bytes. The copies are done from source to destination and then back and the
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source walks forward across the array and the destination walks backward by
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one byte each, thus measuring misaligned accesses as well. The idea is to
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avoid caching effects by copying a different string and far enough from each
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other, walking in different directions so that we can measure prefetcher
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efficiency (software or hardware) more closely than with a loop copying the
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same data over and over, which eventually only gives us L1 cache
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performance. */
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#ifndef MEMCPY_RESULT
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# define MEMCPY_RESULT(dst, len) dst
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# define START_SIZE 128
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# define MIN_PAGE_SIZE (getpagesize () + 32 * 1024 * 1024)
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# define TEST_MAIN
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# define TEST_NAME "memcpy"
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# define TIMEOUT (20 * 60)
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# include "bench-string.h"
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IMPL (memcpy, 1)
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#endif
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#include "json-lib.h"
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typedef char *(*proto_t) (char *, const char *, size_t);
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static void
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do_one_test (json_ctx_t *json_ctx, impl_t *impl, char *dst, char *src,
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size_t len)
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{
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size_t i = 0;
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timing_t start, stop, cur;
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char *dst_end = dst + MIN_PAGE_SIZE - len;
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char *src_end = src + MIN_PAGE_SIZE - len;
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TIMING_NOW (start);
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/* Copy the entire buffer backwards, LEN at a time. */
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for (; src_end >= src && dst_end >= dst; src_end -= len, dst_end -= len, i++)
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CALL (impl, src_end, dst_end, len);
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TIMING_NOW (stop);
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TIMING_DIFF (cur, start, stop);
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/* Get time taken per function call. */
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json_element_double (json_ctx, (double) cur / i);
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}
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static void
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do_test (json_ctx_t *json_ctx, size_t len, int both_ways)
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{
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char *s1, *s2;
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size_t repeats;
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s1 = (char *) (buf1);
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s2 = (char *) (buf2);
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for (repeats = both_ways ? 2 : 1; repeats; --repeats)
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{
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json_element_object_begin (json_ctx);
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json_attr_uint (json_ctx, "length", (double) len);
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json_attr_uint (json_ctx, "dst > src", (double) (s2 > s1));
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json_array_begin (json_ctx, "timings");
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FOR_EACH_IMPL (impl, 0)
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do_one_test (json_ctx, impl, s2, s1, len);
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json_array_end (json_ctx);
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json_element_object_end (json_ctx);
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s1 = (char *) (buf2);
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s2 = (char *) (buf1);
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}
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}
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int
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test_main (void)
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{
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json_ctx_t json_ctx;
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test_init ();
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json_init (&json_ctx, 0, stdout);
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json_document_begin (&json_ctx);
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json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
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json_attr_object_begin (&json_ctx, "functions");
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json_attr_object_begin (&json_ctx, "memcpy");
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json_attr_string (&json_ctx, "bench-variant", "walk");
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json_array_begin (&json_ctx, "ifuncs");
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FOR_EACH_IMPL (impl, 0)
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json_element_string (&json_ctx, impl->name);
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json_array_end (&json_ctx);
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json_array_begin (&json_ctx, "results");
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for (size_t i = START_SIZE; i <= MIN_PAGE_SIZE; i <<= 1)
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{
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do_test (&json_ctx, i, 1);
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do_test (&json_ctx, i + 1, 1);
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}
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json_array_end (&json_ctx);
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json_attr_object_end (&json_ctx);
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json_attr_object_end (&json_ctx);
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json_document_end (&json_ctx);
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return ret;
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}
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#include <support/test-driver.c>
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