From 6a5d6ea128153f5a00d8c80f15f76004006767da Mon Sep 17 00:00:00 2001 From: Torvald Riegel Date: Tue, 8 Oct 2013 14:17:01 +0300 Subject: [PATCH] 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). --- ChangeLog | 6 ++++++ benchtests/Makefile | 3 ++- benchtests/README | 2 ++ benchtests/pthread_once-inputs | 9 +++++++++ benchtests/pthread_once-source.c | 25 +++++++++++++++++++++++++ 5 files changed, 44 insertions(+), 1 deletion(-) create mode 100644 benchtests/pthread_once-inputs create mode 100644 benchtests/pthread_once-source.c diff --git a/ChangeLog b/ChangeLog index 7cc48ce4e8..fb0177d554 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2014-04-10 Torvald Riegel + + * benchtests/pthread_once-inputs: New file. + * benchtests/pthread_once-source.c: New file. + * benchtests/README: Update documentation. + 2014-04-09 Igor Zamyatin H.J. Lu diff --git a/benchtests/Makefile b/benchtests/Makefile index ca635cfe85..6e3f86bbe8 100644 --- a/benchtests/Makefile +++ b/benchtests/Makefile @@ -23,7 +23,7 @@ subdir := benchtests include ../Makeconfig bench := acos acosh asin asinh atan atanh cos cosh exp exp2 ffs ffsll \ - log log2 modf pow rint sin sincos sinh sqrt tan tanh + log log2 modf pow pthread_once rint sin sincos sinh sqrt tan tanh # String function benchmarks. string-bench := bcopy bzero memccpy memchr memcmp memcpy memmem memmove \ @@ -53,6 +53,7 @@ LDLIBS-bench-exp2 = -lm LDLIBS-bench-log = -lm LDLIBS-bench-log2 = -lm LDLIBS-bench-pow = -lm +LDLIBS-bench-pthread_once = -lpthread LDLIBS-bench-rint = -lm LDLIBS-bench-sin = -lm LDLIBS-bench-sinh = -lm diff --git a/benchtests/README b/benchtests/README index 2a940fab7f..52a3cc2062 100644 --- a/benchtests/README +++ b/benchtests/README @@ -60,6 +60,8 @@ one to add `foo' to the bench tests: - include-sources: This should be assigned a comma-separated list of source files that need to be included to provide definitions of global variables and functions (specifically, this includes using "#include "source"). + See pthread_once-inputs and pthreads_once-source.c for an example of how + to use this to benchmark a function that needs state across several calls. - name: See following section for instructions on how to use this directive. Lines beginning with a single hash '#' are treated as comments. See diff --git a/benchtests/pthread_once-inputs b/benchtests/pthread_once-inputs new file mode 100644 index 0000000000..22c57096f7 --- /dev/null +++ b/benchtests/pthread_once-inputs @@ -0,0 +1,9 @@ +# This tests the common-case scenario for pthread_once. +# 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. +# scripts/bench.py doesn't handle function pointers, so we just use void *: +## args: pthread_once_t *:void * +## includes: pthread.h +## include-sources: pthread_once-source.c +&once, once_handler diff --git a/benchtests/pthread_once-source.c b/benchtests/pthread_once-source.c new file mode 100644 index 0000000000..5f98b0a3b3 --- /dev/null +++ b/benchtests/pthread_once-source.c @@ -0,0 +1,25 @@ +/* Measure pthread_once best-case latency (i.e., when already initialized. + + Copyright (C) 2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +static pthread_once_t once = PTHREAD_ONCE_INIT; + +static void +once_handler (void) +{ +}