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0edbf12301
Current allocate_stack logic for create stacks is to first mmap all
the required memory with the desirable memory and then mprotect the
guard area with PROT_NONE if required. Although it works as expected,
it pessimizes the allocation because it requires the kernel to actually
increase commit charge (it counts against the available physical/swap
memory available for the system).
The only issue is to actually check this change since side-effects are
really Linux specific and to actually account them it would require a
kernel specific tests to parse the system wide information. On the kernel
I checked /proc/self/statm does not show any meaningful difference for
vmm and/or rss before and after thread creation. I could only see
really meaningful information checking on system wide /proc/meminfo
between thread creation: MemFree, MemAvailable, and Committed_AS shows
large difference without the patch. I think trying to use these
kind of information on a testcase is fragile.
The BZ#18988 reports shows that the commit pages are easily seen with
mlockall (MCL_FUTURE) (with lock all pages that become mapped in the
process) however a more straighfoward testcase shows that pthread_create
could be faster using this patch:
--
static const int inner_count = 256;
static const int outer_count = 128;
static
void *thread1(void *arg)
{
return NULL;
}
static
void *sleeper(void *arg)
{
pthread_t ts[inner_count];
for (int i = 0; i < inner_count; i++)
pthread_create (&ts[i], &a, thread1, NULL);
for (int i = 0; i < inner_count; i++)
pthread_join (ts[i], NULL);
return NULL;
}
int main(void)
{
pthread_attr_init(&a);
pthread_attr_setguardsize(&a, 1<<20);
pthread_attr_setstacksize(&a, 1134592);
pthread_t ts[outer_count];
for (int i = 0; i < outer_count; i++)
pthread_create(&ts[i], &a, sleeper, NULL);
for (int i = 0; i < outer_count; i++)
pthread_join(ts[i], NULL);
assert(r == 0);
}
return 0;
}
--
On x86_64 (4.4.0-45-generic, gcc 5.4.0) running the small benchtests
I see:
$ time ./test
real 0m3.647s
user 0m0.080s
sys 0m11.836s
While with the patch I see:
$ time ./test
real 0m0.696s
user 0m0.040s
sys 0m1.152s
So I added a pthread_create benchtest (thread_create) which check
the thread creation latency. As for the simple benchtests, I saw
improvements in thread creation on all architectures I tested the
change.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
arm-linux-gnueabihf, powerpc64le-linux-gnu, sparc64-linux-gnu,
and sparcv9-linux-gnu.
[BZ #18988]
* benchtests/thread_create-inputs: New file.
* benchtests/thread_create-source.c: Likewise.
* support/xpthread_attr_setguardsize.c: Likewise.
* support/Makefile (libsupport-routines): Add
xpthread_attr_setguardsize object.
* support/xthread.h: Add xpthread_attr_setguardsize prototype.
* benchtests/Makefile (bench-pthread): Add thread_create.
* nptl/allocatestack.c (allocate_stack): Call mmap with PROT_NONE and
then mprotect the required area.
148 lines
3.6 KiB
Makefile
148 lines
3.6 KiB
Makefile
# Makefile for support library, used only at build and test time
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# Copyright (C) 2016-2017 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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subdir := support
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include ../Makeconfig
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extra-libs := libsupport
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extra-libs-others = $(extra-libs)
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extra-libs-noinstall := $(extra-libs)
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libsupport-routines = \
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check \
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check_addrinfo \
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check_dns_packet \
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check_hostent \
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check_netent \
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delayed_exit \
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ignore_stderr \
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oom_error \
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resolv_test \
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set_fortify_handler \
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support-xstat \
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support_become_root \
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support_can_chroot \
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support_capture_subprocess \
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support_capture_subprocess_check \
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support_enter_network_namespace \
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support_format_address_family \
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support_format_addrinfo \
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support_format_dns_packet \
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support_format_herrno \
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support_format_hostent \
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support_format_netent \
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support_isolate_in_subprocess \
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support_record_failure \
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support_run_diff \
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support_shared_allocate \
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support_write_file_string \
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support_test_main \
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support_test_verify_impl \
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temp_file \
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write_message \
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xaccept \
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xaccept4 \
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xasprintf \
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xbind \
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xcalloc \
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xchroot \
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xclose \
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xconnect \
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xdup2 \
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xfclose \
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xfopen \
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xfork \
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xgetsockname \
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xlisten \
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xmalloc \
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xmemstream \
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xmkdir \
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xmmap \
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xmunmap \
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xopen \
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xpipe \
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xpoll \
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xpthread_attr_destroy \
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xpthread_attr_init \
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xpthread_attr_setdetachstate \
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xpthread_attr_setstacksize \
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xpthread_attr_setguardsize \
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xpthread_barrier_destroy \
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xpthread_barrier_init \
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xpthread_barrier_wait \
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xpthread_cancel \
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xpthread_check_return \
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xpthread_cond_wait \
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xpthread_create \
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xpthread_detach \
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xpthread_join \
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xpthread_mutex_consistent \
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xpthread_mutex_destroy \
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xpthread_mutex_init \
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xpthread_mutex_lock \
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xpthread_mutex_unlock \
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xpthread_mutexattr_destroy \
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xpthread_mutexattr_init \
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xpthread_mutexattr_setprotocol \
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xpthread_mutexattr_setpshared \
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xpthread_mutexattr_setrobust \
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xpthread_mutexattr_settype \
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xpthread_once \
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xpthread_sigmask \
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xpthread_spin_lock \
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xpthread_spin_unlock \
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xrealloc \
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xrecvfrom \
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xsendto \
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xsetsockopt \
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xsocket \
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xstrdup \
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xwaitpid \
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xwrite \
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libsupport-static-only-routines := $(libsupport-routines)
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# Only build one variant of the library.
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libsupport-inhibit-o := .os
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ifeq ($(build-shared),yes)
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libsupport-inhibit-o += .o
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endif
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tests = \
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README-testing \
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tst-support-namespace \
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tst-support_capture_subprocess \
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tst-support_format_dns_packet \
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tst-support_record_failure \
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ifeq ($(run-built-tests),yes)
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tests-special = \
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$(objpfx)tst-support_record_failure-2.out
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$(objpfx)tst-support_record_failure-2.out: tst-support_record_failure-2.sh \
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$(objpfx)tst-support_record_failure
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$(SHELL) $< $(common-objpfx) '$(test-program-prefix-before-env)' \
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'$(run-program-env)' '$(test-program-prefix-after-env)' \
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> $@; \
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$(evaluate-test)
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endif
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$(objpfx)tst-support_format_dns_packet: $(common-objpfx)resolv/libresolv.so
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include ../Rules
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