mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-29 08:11:08 +00:00
ed2f9aaf5e
This is a new implementation of GSCOPE which largely mirrors its NPTL counterpart. Same as in NPTL, instead of a global flag shared between threads, there is now a per-thread GSCOPE flag stored in each thread's TCB. This makes entering and exiting a GSCOPE faster at the expense of making THREAD_GSCOPE_WAIT () slower. The largest win is the elimination of many redundant gsync_wake () RPC calls; previously, even simplest programs would make dozens of fully redundant gsync_wake () calls. Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> Message-Id: <20210915171110.226187-3-bugaevc@gmail.com> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
/* Out-of-line notification function for the GSCOPE locking mechanism.
|
|
Copyright (C) 2007-2021 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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <ldsodefs.h>
|
|
#include <pthread.h>
|
|
#include <htl/pt-internal.h>
|
|
|
|
void
|
|
__thread_gscope_wait (void)
|
|
{
|
|
size_t i;
|
|
struct __pthread *t;
|
|
int *gscope_flagp;
|
|
|
|
__libc_rwlock_rdlock (GL (dl_pthread_threads_lock));
|
|
|
|
/* Iterate over the list of threads. */
|
|
for (i = 0; i < GL (dl_pthread_num_threads); ++i)
|
|
{
|
|
t = GL (dl_pthread_threads[i]);
|
|
if (t == NULL || t->tcb->gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
|
|
continue;
|
|
|
|
gscope_flagp = &t->tcb->gscope_flag;
|
|
|
|
/* We have to wait until this thread is done with the global
|
|
scope. First tell the thread that we are waiting and
|
|
possibly have to be woken. */
|
|
if (atomic_compare_and_exchange_bool_acq (gscope_flagp,
|
|
THREAD_GSCOPE_FLAG_WAIT,
|
|
THREAD_GSCOPE_FLAG_USED))
|
|
continue;
|
|
|
|
do
|
|
lll_wait (gscope_flagp, THREAD_GSCOPE_FLAG_WAIT, LLL_PRIVATE);
|
|
while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
|
|
}
|
|
|
|
__libc_rwlock_unlock (GL (dl_pthread_threads_lock));
|
|
}
|