1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
/* 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)
|
