glibc/nptl/nptl-stack.c
Florian Weimer c79a31fb36 nptl: Move stack cache management, __libpthread_freeres into libc
This replaces the FREE_P macro with the __nptl_stack_in_use inline
function.  stack_list_del is renamed to __nptl_stack_list_del,
stack_list_add to __nptl_stack_list_add, __deallocate_stack to
__nptl_deallocate_stack, free_stacks to __nptl_free_stacks.

It is convenient to move __libpthread_freeres into libc at the
same time.  This removes the temporary __default_pthread_attr_freeres
export and restores full freeres coverage for __default_pthread_attr.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2021-05-11 11:22:33 +02:00

131 lines
3.8 KiB
C

/* Stack cache management for NPTL.
Copyright (C) 2002-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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 <nptl-stack.h>
#include <ldsodefs.h>
/* Maximum size in kB of cache. 40MiBi by default. */
static const size_t stack_cache_maxsize = 40 * 1024 * 1024;
void
__nptl_stack_list_del (list_t *elem)
{
GL (dl_in_flight_stack) = (uintptr_t) elem;
atomic_write_barrier ();
list_del (elem);
atomic_write_barrier ();
GL (dl_in_flight_stack) = 0;
}
libc_hidden_def (__nptl_stack_list_del)
void
__nptl_stack_list_add (list_t *elem, list_t *list)
{
GL (dl_in_flight_stack) = (uintptr_t) elem | 1;
atomic_write_barrier ();
list_add (elem, list);
atomic_write_barrier ();
GL (dl_in_flight_stack) = 0;
}
libc_hidden_def (__nptl_stack_list_add)
void
__nptl_free_stacks (size_t limit)
{
/* We reduce the size of the cache. Remove the last entries until
the size is below the limit. */
list_t *entry;
list_t *prev;
/* Search from the end of the list. */
list_for_each_prev_safe (entry, prev, &GL (dl_stack_cache))
{
struct pthread *curr;
curr = list_entry (entry, struct pthread, list);
if (__nptl_stack_in_use (curr))
{
/* Unlink the block. */
__nptl_stack_list_del (entry);
/* Account for the freed memory. */
GL (dl_stack_cache_actsize) -= curr->stackblock_size;
/* Free the memory associated with the ELF TLS. */
_dl_deallocate_tls (TLS_TPADJ (curr), false);
/* Remove this block. This should never fail. If it does
something is really wrong. */
if (__munmap (curr->stackblock, curr->stackblock_size) != 0)
abort ();
/* Maybe we have freed enough. */
if (GL (dl_stack_cache_actsize) <= limit)
break;
}
}
}
/* Add a stack frame which is not used anymore to the stack. Must be
called with the cache lock held. */
static inline void
__attribute ((always_inline))
queue_stack (struct pthread *stack)
{
/* We unconditionally add the stack to the list. The memory may
still be in use but it will not be reused until the kernel marks
the stack as not used anymore. */
__nptl_stack_list_add (&stack->list, &GL (dl_stack_cache));
GL (dl_stack_cache_actsize) += stack->stackblock_size;
if (__glibc_unlikely (GL (dl_stack_cache_actsize) > stack_cache_maxsize))
__nptl_free_stacks (stack_cache_maxsize);
}
void
__nptl_deallocate_stack (struct pthread *pd)
{
lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
/* Remove the thread from the list of threads with user defined
stacks. */
__nptl_stack_list_del (&pd->list);
/* Not much to do. Just free the mmap()ed memory. Note that we do
not reset the 'used' flag in the 'tid' field. This is done by
the kernel. If no thread has been created yet this field is
still zero. */
if (__glibc_likely (! pd->user_stack))
(void) queue_stack (pd);
else
/* Free the memory associated with the ELF TLS. */
_dl_deallocate_tls (TLS_TPADJ (pd), false);
lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
}
libc_hidden_def (__nptl_deallocate_stack)