src/vm-limit.c

   1 /* Functions for memory limit warnings.
   2    Copyright (C) 1990, 1992, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
   3                  2008, 2009, 2010  Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software: you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation, either version 3 of the License, or
  10 (at your option) any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifdef emacs
  21 #include <config.h>
  22 #include <setjmp.h>
  23 #include "lisp.h"
  24 #endif
  25
  26 #include "mem-limits.h"
  27
  28 /*
  29   Level number of warnings already issued.
  30   0 -- no warnings issued.
  31   1 -- 75% warning already issued.
  32   2 -- 85% warning already issued.
  33   3 -- 95% warning issued; keep warning frequently.
  34 */
  35 enum warnlevel { not_warned, warned_75, warned_85, warned_95 };
  36 static enum warnlevel warnlevel;
  37
  38 typedef POINTER_TYPE *POINTER;
  39
  40 /* Function to call to issue a warning;
  41    0 means don't issue them.  */
  42 static void (*warn_function) (const char *);
  43
  44 /* Start of data space; can be changed by calling malloc_init.  */
  45 static POINTER data_space_start;
  46
  47 /* Number of bytes of writable memory we can expect to be able to get.  */
  48 static unsigned long lim_data;
  49 \f
  50
  51 #if defined (HAVE_GETRLIMIT) && defined (RLIMIT_AS)
  52 static void
  53 get_lim_data (void)
  54 {
  55   struct rlimit rlimit;
  56
  57   getrlimit (RLIMIT_AS, &rlimit);
  58   if (rlimit.rlim_cur == RLIM_INFINITY)
  59     lim_data = -1;
  60   else
  61     lim_data = rlimit.rlim_cur;
  62 }
  63
  64 #else /* not HAVE_GETRLIMIT */
  65
  66 #ifdef USG
  67
  68 static void
  69 get_lim_data (void)
  70 {
  71   extern long ulimit ();
  72
  73   lim_data = -1;
  74
  75   /* Use the ulimit call, if we seem to have it.  */
  76 #if !defined (ULIMIT_BREAK_VALUE) || defined (GNU_LINUX)
  77   lim_data = ulimit (3, 0);
  78 #endif
  79
  80   /* If that didn't work, just use the macro's value.  */
  81 #ifdef ULIMIT_BREAK_VALUE
  82   if (lim_data == -1)
  83     lim_data = ULIMIT_BREAK_VALUE;
  84 #endif
  85
  86   lim_data -= (long) data_space_start;
  87 }
  88
  89 #else /* not USG */
  90 #ifdef WINDOWSNT
  91
  92 static void
  93 get_lim_data (void)
  94 {
  95   extern unsigned long reserved_heap_size;
  96   lim_data = reserved_heap_size;
  97 }
  98
  99 #else
 100 #if !defined (BSD4_2) && !defined (CYGWIN)
 101
 102 #ifdef MSDOS
 103 void
 104 get_lim_data (void)
 105 {
 106   _go32_dpmi_meminfo info;
 107   unsigned long lim1, lim2;
 108
 109   _go32_dpmi_get_free_memory_information (&info);
 110   /* DPMI server of Windows NT and its descendants reports in
 111      info.available_memory a much lower amount that is really
 112      available, which causes bogus "past 95% of memory limit"
 113      warnings.  Try to overcome that via circumstantial evidence.  */
 114   lim1 = info.available_memory;
 115   lim2 = info.available_physical_pages;
 116   /* DPMI Spec: "Fields that are unavailable will hold -1."  */
 117   if ((long)lim1 == -1L)
 118     lim1 = 0;
 119   if ((long)lim2 == -1L)
 120     lim2 = 0;
 121   else
 122     lim2 *= 4096;
 123   /* Surely, the available memory is at least what we have physically
 124      available, right?  */
 125   if (lim1 >= lim2)
 126     lim_data = lim1;
 127   else
 128     lim_data = lim2;
 129   /* Don't believe they will give us more that 0.5 GB.   */
 130   if (lim_data > 512U * 1024U * 1024U)
 131     lim_data = 512U * 1024U * 1024U;
 132 }
 133
 134 unsigned long
 135 ret_lim_data (void)
 136 {
 137   get_lim_data ();
 138   return lim_data;
 139 }
 140 #else /* not MSDOS */
 141 static void
 142 get_lim_data (void)
 143 {
 144   lim_data = vlimit (LIM_DATA, -1);
 145 }
 146 #endif /* not MSDOS */
 147
 148 #else /* BSD4_2 || CYGWIN */
 149
 150 static void
 151 get_lim_data (void)
 152 {
 153   struct rlimit XXrlimit;
 154
 155   getrlimit (RLIMIT_DATA, &XXrlimit);
 156 #ifdef RLIM_INFINITY
 157   lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
 158 #else
 159   lim_data = XXrlimit.rlim_cur; /* soft limit */
 160 #endif
 161 }
 162 #endif /* BSD4_2 */
 163 #endif /* not WINDOWSNT */
 164 #endif /* not USG */
 165 #endif /* not HAVE_GETRLIMIT */
 166 \f
 167 /* Verify amount of memory available, complaining if we're near the end. */
 168
 169 static void
 170 check_memory_limits (void)
 171 {
 172 #ifdef REL_ALLOC
 173   extern POINTER (*real_morecore) (SIZE);
 174 #endif
 175   extern POINTER (*__morecore) (SIZE);
 176
 177   register POINTER cp;
 178   unsigned long five_percent;
 179   unsigned long data_size;
 180   enum warnlevel new_warnlevel;
 181
 182   if (lim_data == 0)
 183     get_lim_data ();
 184   five_percent = lim_data / 20;
 185
 186   /* Find current end of memory and issue warning if getting near max */
 187 #ifdef REL_ALLOC
 188   if (real_morecore)
 189     cp = (char *) (*real_morecore) (0);
 190   else
 191 #endif
 192   cp = (char *) (*__morecore) (0);
 193   data_size = (char *) cp - (char *) data_space_start;
 194
 195   if (!warn_function)
 196     return;
 197
 198   /* What level of warning does current memory usage demand?  */
 199   new_warnlevel
 200     = (data_size > five_percent * 19) ? warned_95
 201     : (data_size > five_percent * 17) ? warned_85
 202     : (data_size > five_percent * 15) ? warned_75
 203     : not_warned;
 204
 205   /* If we have gone up a level, give the appropriate warning.  */
 206   if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
 207     {
 208       warnlevel = new_warnlevel;
 209       switch (warnlevel)
 210         {
 211         case warned_75:
 212           (*warn_function) ("Warning: past 75% of memory limit");
 213           break;
 214
 215         case warned_85:
 216           (*warn_function) ("Warning: past 85% of memory limit");
 217           break;
 218
 219         case warned_95:
 220           (*warn_function) ("Warning: past 95% of memory limit");
 221         }
 222     }
 223   /* Handle going down in usage levels, with some hysteresis.  */
 224   else
 225     {
 226       /* If we go down below 70% full, issue another 75% warning
 227          when we go up again.  */
 228       if (data_size < five_percent * 14)
 229         warnlevel = not_warned;
 230       /* If we go down below 80% full, issue another 85% warning
 231          when we go up again.  */
 232       else if (warnlevel > warned_75 && data_size < five_percent * 16)
 233         warnlevel = warned_75;
 234       /* If we go down below 90% full, issue another 95% warning
 235          when we go up again.  */
 236       else if (warnlevel > warned_85 && data_size < five_percent * 18)
 237         warnlevel = warned_85;
 238     }
 239
 240   if (EXCEEDS_LISP_PTR (cp))
 241     (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
 242 }
 243 \f
 244 #if !defined(CANNOT_DUMP) || !defined(SYSTEM_MALLOC)
 245 /* Some systems that cannot dump also cannot implement these.  */
 246
 247 /*
 248  *      Return the address of the start of the data segment prior to
 249  *      doing an unexec.  After unexec the return value is undefined.
 250  *      See crt0.c for further information and definition of data_start.
 251  *
 252  *      Apparently, on BSD systems this is etext at startup.  On
 253  *      USG systems (swapping) this is highly mmu dependent and
 254  *      is also dependent on whether or not the program is running
 255  *      with shared text.  Generally there is a (possibly large)
 256  *      gap between end of text and start of data with shared text.
 257  *
 258  */
 259
 260 char *
 261 start_of_data (void)
 262 {
 263 #ifdef BSD_SYSTEM
 264   extern char etext;
 265   return (POINTER)(&etext);
 266 #elif defined DATA_START
 267   return ((POINTER) DATA_START);
 268 #elif defined ORDINARY_LINK
 269   /*
 270    * This is a hack.  Since we're not linking crt0.c or pre_crt0.c,
 271    * data_start isn't defined.  We take the address of environ, which
 272    * is known to live at or near the start of the system crt0.c, and
 273    * we don't sweat the handful of bytes that might lose.
 274    */
 275   extern char **environ;
 276   return ((POINTER) &environ);
 277 #else
 278   extern int data_start;
 279   return ((POINTER) &data_start);
 280 #endif
 281 }
 282 #endif /* (not CANNOT_DUMP or not SYSTEM_MALLOC) */
 283 \f
 284 /* Enable memory usage warnings.
 285    START says where the end of pure storage is.
 286    WARNFUN specifies the function to call to issue a warning.  */
 287
 288 void
 289 memory_warnings (POINTER start, void (*warnfun) (const char *))
 290 {
 291   extern void (* __after_morecore_hook) (void);     /* From gmalloc.c */
 292
 293   if (start)
 294     data_space_start = start;
 295   else
 296     data_space_start = start_of_data ();
 297
 298   warn_function = warnfun;
 299   __after_morecore_hook = check_memory_limits;
 300
 301   /* Force data limit to be recalculated on each run.  */
 302   lim_data = 0;
 303 }
 304
 305 /* arch-tag: eab04eda-1f69-447a-8d9f-95f0a3983ca5
 306    (do not change this comment) */