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The existing speed checks time one call at one size, 128 bytes, with both operands aligned. A machine implementation usually takes its wide path only when the pointers satisfy some alignment condition, so that single point reports the best case and says nothing about the rest of the input space. Measure the same functions across a size sweep and every source and destination alignment pair instead, plus strlcpy. On rv64 the difference this exposes is not marginal: strcpy 32768 B s+0/d+0 2938.0 MB/s strcpy 32768 B s+1/d+1 2942.0 MB/s strcpy 32768 B s+1/d+2 626.0 MB/s memcmp 32768 B s+0/d+0 412.4 MB/s memcmp 32768 B s+1/d+2 41.0 MB/s Two pointers misaligned by the same amount run at the aligned rate; misaligned by different amounts they fall to a tenth of it. Neither number is visible from an aligned measurement alone. A function with no machine implementation reports the same rate at every alignment, so the sweep also shows which of them a machine directory actually covers. Each result reports MB/s, which compares across machines, and cycles per byte where perf_gettime() is reachable from an application, both from one timed loop. strcat starts from an empty destination on each turn, since appending to the last result would grow it without bound, so its figure includes that store. It sits behind TESTING_ARCH_LIBC_BENCH, default n, because a measurement runs for a fixed interval and a full sweep takes about a minute. Assisted-by: Claude:claude-opus-5 Signed-off-by: Justin Hammond <justin@dynam.ac>
40 lines
1.4 KiB
Makefile
40 lines
1.4 KiB
Makefile
############################################################################
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# apps/testing/libc/arch_libc/Makefile
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#
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# SPDX-License-Identifier: Apache-2.0
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#
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# Licensed to the Apache Software Foundation (ASF) under one or more
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# contributor license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright ownership. The
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# ASF licenses this file to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance with the
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# License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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#
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############################################################################
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include $(APPDIR)/Make.defs
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# test application info
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PROGNAME = $(CONFIG_TESTING_ARCH_LIBC_PROGNAME)
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PRIORITY = $(CONFIG_TESTING_ARCH_LIBC_PRIORITY)
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STACKSIZE = $(CONFIG_TESTING_ARCH_LIBC_STACKSIZE)
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MODULE = $(CONFIG_TESTING_ARCH_LIBC)
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# arch libc test
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ifneq ($(CONFIG_TESTING_ARCH_LIBC_BENCH),)
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CSRCS += arch_libc_bench.c
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endif
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MAINSRC = arch_libc_test_main.c
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include $(APPDIR)/Application.mk
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