src/xdisp.c (single_display_spec_string): Correct a FIXME comment.
[emacs.git] / src / vm-limit.c
blob4694608602fe14b85669f286609501a985cfd21f
1 /* Functions for memory limit warnings.
2 Copyright (C) 1990, 1992, 2001-2011 Free Software Foundation, Inc.
4 This file is part of GNU Emacs.
6 GNU Emacs is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 GNU Emacs is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
19 #include <config.h>
20 #include <setjmp.h>
21 #include "lisp.h"
22 #include "mem-limits.h"
25 Level number of warnings already issued.
26 0 -- no warnings issued.
27 1 -- 75% warning already issued.
28 2 -- 85% warning already issued.
29 3 -- 95% warning issued; keep warning frequently.
31 enum warnlevel { not_warned, warned_75, warned_85, warned_95 };
32 static enum warnlevel warnlevel;
34 typedef POINTER_TYPE *POINTER;
36 /* Function to call to issue a warning;
37 0 means don't issue them. */
38 static void (*warn_function) (const char *);
40 /* Start of data space; can be changed by calling malloc_init. */
41 static POINTER data_space_start;
43 /* Number of bytes of writable memory we can expect to be able to get. */
44 static unsigned long lim_data;
47 #if defined (HAVE_GETRLIMIT) && defined (RLIMIT_AS)
48 static void
49 get_lim_data (void)
51 struct rlimit rlimit;
53 getrlimit (RLIMIT_AS, &rlimit);
54 if (rlimit.rlim_cur == RLIM_INFINITY)
55 lim_data = -1;
56 else
57 lim_data = rlimit.rlim_cur;
60 #else /* not HAVE_GETRLIMIT */
62 #ifdef USG
64 static void
65 get_lim_data (void)
67 extern long ulimit ();
69 lim_data = -1;
71 /* Use the ulimit call, if we seem to have it. */
72 #if !defined (ULIMIT_BREAK_VALUE) || defined (GNU_LINUX)
73 lim_data = ulimit (3, 0);
74 #endif
76 /* If that didn't work, just use the macro's value. */
77 #ifdef ULIMIT_BREAK_VALUE
78 if (lim_data == -1)
79 lim_data = ULIMIT_BREAK_VALUE;
80 #endif
82 lim_data -= (long) data_space_start;
85 #else /* not USG */
86 #ifdef WINDOWSNT
88 static void
89 get_lim_data (void)
91 extern unsigned long reserved_heap_size;
92 lim_data = reserved_heap_size;
95 #else
96 #if !defined (BSD4_2) && !defined (CYGWIN)
98 #ifdef MSDOS
99 void
100 get_lim_data (void)
102 _go32_dpmi_meminfo info;
103 unsigned long lim1, lim2;
105 _go32_dpmi_get_free_memory_information (&info);
106 /* DPMI server of Windows NT and its descendants reports in
107 info.available_memory a much lower amount that is really
108 available, which causes bogus "past 95% of memory limit"
109 warnings. Try to overcome that via circumstantial evidence. */
110 lim1 = info.available_memory;
111 lim2 = info.available_physical_pages;
112 /* DPMI Spec: "Fields that are unavailable will hold -1." */
113 if ((long)lim1 == -1L)
114 lim1 = 0;
115 if ((long)lim2 == -1L)
116 lim2 = 0;
117 else
118 lim2 *= 4096;
119 /* Surely, the available memory is at least what we have physically
120 available, right? */
121 if (lim1 >= lim2)
122 lim_data = lim1;
123 else
124 lim_data = lim2;
125 /* Don't believe they will give us more that 0.5 GB. */
126 if (lim_data > 512U * 1024U * 1024U)
127 lim_data = 512U * 1024U * 1024U;
130 unsigned long
131 ret_lim_data (void)
133 get_lim_data ();
134 return lim_data;
136 #else /* not MSDOS */
137 static void
138 get_lim_data (void)
140 lim_data = vlimit (LIM_DATA, -1);
142 #endif /* not MSDOS */
144 #else /* BSD4_2 || CYGWIN */
146 static void
147 get_lim_data (void)
149 struct rlimit XXrlimit;
151 getrlimit (RLIMIT_DATA, &XXrlimit);
152 #ifdef RLIM_INFINITY
153 lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
154 #else
155 lim_data = XXrlimit.rlim_cur; /* soft limit */
156 #endif
158 #endif /* BSD4_2 */
159 #endif /* not WINDOWSNT */
160 #endif /* not USG */
161 #endif /* not HAVE_GETRLIMIT */
163 /* Verify amount of memory available, complaining if we're near the end. */
165 static void
166 check_memory_limits (void)
168 #ifdef REL_ALLOC
169 extern POINTER (*real_morecore) (SIZE);
170 #endif
171 extern POINTER (*__morecore) (SIZE);
173 register POINTER cp;
174 unsigned long five_percent;
175 unsigned long data_size;
176 enum warnlevel new_warnlevel;
178 if (lim_data == 0)
179 get_lim_data ();
180 five_percent = lim_data / 20;
182 /* Find current end of memory and issue warning if getting near max */
183 #ifdef REL_ALLOC
184 if (real_morecore)
185 cp = (char *) (*real_morecore) (0);
186 else
187 #endif
188 cp = (char *) (*__morecore) (0);
189 data_size = (char *) cp - (char *) data_space_start;
191 if (!warn_function)
192 return;
194 /* What level of warning does current memory usage demand? */
195 new_warnlevel
196 = (data_size > five_percent * 19) ? warned_95
197 : (data_size > five_percent * 17) ? warned_85
198 : (data_size > five_percent * 15) ? warned_75
199 : not_warned;
201 /* If we have gone up a level, give the appropriate warning. */
202 if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
204 warnlevel = new_warnlevel;
205 switch (warnlevel)
207 case warned_75:
208 (*warn_function) ("Warning: past 75% of memory limit");
209 break;
211 case warned_85:
212 (*warn_function) ("Warning: past 85% of memory limit");
213 break;
215 case warned_95:
216 (*warn_function) ("Warning: past 95% of memory limit");
219 /* Handle going down in usage levels, with some hysteresis. */
220 else
222 /* If we go down below 70% full, issue another 75% warning
223 when we go up again. */
224 if (data_size < five_percent * 14)
225 warnlevel = not_warned;
226 /* If we go down below 80% full, issue another 85% warning
227 when we go up again. */
228 else if (warnlevel > warned_75 && data_size < five_percent * 16)
229 warnlevel = warned_75;
230 /* If we go down below 90% full, issue another 95% warning
231 when we go up again. */
232 else if (warnlevel > warned_85 && data_size < five_percent * 18)
233 warnlevel = warned_85;
236 if (EXCEEDS_LISP_PTR (cp))
237 (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
240 #if !defined(CANNOT_DUMP) || !defined(SYSTEM_MALLOC)
241 /* Some systems that cannot dump also cannot implement these. */
244 * Return the address of the start of the data segment prior to
245 * doing an unexec. After unexec the return value is undefined.
246 * See crt0.c for further information and definition of data_start.
248 * Apparently, on BSD systems this is etext at startup. On
249 * USG systems (swapping) this is highly mmu dependent and
250 * is also dependent on whether or not the program is running
251 * with shared text. Generally there is a (possibly large)
252 * gap between end of text and start of data with shared text.
256 char *
257 start_of_data (void)
259 #ifdef BSD_SYSTEM
260 extern char etext;
261 return (POINTER)(&etext);
262 #elif defined DATA_START
263 return ((POINTER) DATA_START);
264 #elif defined ORDINARY_LINK
266 * This is a hack. Since we're not linking crt0.c or pre_crt0.c,
267 * data_start isn't defined. We take the address of environ, which
268 * is known to live at or near the start of the system crt0.c, and
269 * we don't sweat the handful of bytes that might lose.
271 extern char **environ;
272 return ((POINTER) &environ);
273 #else
274 extern int data_start;
275 return ((POINTER) &data_start);
276 #endif
278 #endif /* (not CANNOT_DUMP or not SYSTEM_MALLOC) */
280 /* Enable memory usage warnings.
281 START says where the end of pure storage is.
282 WARNFUN specifies the function to call to issue a warning. */
284 void
285 memory_warnings (POINTER start, void (*warnfun) (const char *))
287 extern void (* __after_morecore_hook) (void); /* From gmalloc.c */
289 if (start)
290 data_space_start = start;
291 else
292 data_space_start = start_of_data ();
294 warn_function = warnfun;
295 __after_morecore_hook = check_memory_limits;
297 /* Force data limit to be recalculated on each run. */
298 lim_data = 0;