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benchtests: Add pthread_once common-case test.
We have a single thread that runs a no-op initialization once and then repeatedly runs checks of the initialization (i.e., an acquire load and conditional jump) in a tight loop. This gives us, on average, the best-case latency of pthread_once (the initialization is the exactly-once slow path, and we're not looking at initialization-related synchronization overheads in this case).
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@ -1,3 +1,9 @@
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2014-04-10 Torvald Riegel <triegel@redhat.com>
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* benchtests/pthread_once-inputs: New file.
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* benchtests/pthread_once-source.c: New file.
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* benchtests/README: Update documentation.
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2014-04-09 Igor Zamyatin <igor.zamyatin@intel.com>
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H.J. Lu <hongjiu.lu@intel.com>
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@ -23,7 +23,7 @@ subdir := benchtests
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include ../Makeconfig
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bench := acos acosh asin asinh atan atanh cos cosh exp exp2 ffs ffsll \
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log log2 modf pow rint sin sincos sinh sqrt tan tanh
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log log2 modf pow pthread_once rint sin sincos sinh sqrt tan tanh
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# String function benchmarks.
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string-bench := bcopy bzero memccpy memchr memcmp memcpy memmem memmove \
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@ -53,6 +53,7 @@ LDLIBS-bench-exp2 = -lm
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LDLIBS-bench-log = -lm
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LDLIBS-bench-log2 = -lm
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LDLIBS-bench-pow = -lm
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LDLIBS-bench-pthread_once = -lpthread
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LDLIBS-bench-rint = -lm
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LDLIBS-bench-sin = -lm
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LDLIBS-bench-sinh = -lm
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@ -60,6 +60,8 @@ one to add `foo' to the bench tests:
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- include-sources: This should be assigned a comma-separated list of source
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files that need to be included to provide definitions of global variables
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and functions (specifically, this includes using "#include "source").
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See pthread_once-inputs and pthreads_once-source.c for an example of how
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to use this to benchmark a function that needs state across several calls.
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- name: See following section for instructions on how to use this directive.
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Lines beginning with a single hash '#' are treated as comments. See
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9
benchtests/pthread_once-inputs
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9
benchtests/pthread_once-inputs
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@ -0,0 +1,9 @@
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# This tests the common-case scenario for pthread_once.
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# We have a single thread that runs a no-op initialization once and then
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# repeatedly runs checks of the initialization (i.e., an acquire load and
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# conditional jump) in a tight loop.
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# scripts/bench.py doesn't handle function pointers, so we just use void *:
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## args: pthread_once_t *:void *
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## includes: pthread.h
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## include-sources: pthread_once-source.c
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&once, once_handler
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25
benchtests/pthread_once-source.c
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25
benchtests/pthread_once-source.c
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/* Measure pthread_once best-case latency (i.e., when already initialized.
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Copyright (C) 2014 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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<http://www.gnu.org/licenses/>. */
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static pthread_once_t once = PTHREAD_ONCE_INIT;
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static void
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once_handler (void)
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{
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}
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