src/vm-limit.c

   1 /* Functions for memory limit warnings.
   2    Copyright (C) 1990, 1992, 2001-2012  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   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.
  10
  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.
  15
  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/>.  */
  18
  19 #include <config.h>
  20 #include <setjmp.h>
  21 #include "lisp.h"
  22 #include "mem-limits.h"
  23
  24 /*
  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.
  30 */
  31 enum warnlevel { not_warned, warned_75, warned_85, warned_95 };
  32 static enum warnlevel warnlevel;
  33
  34 typedef void *POINTER;
  35
  36 /* Function to call to issue a warning;
  37    0 means don't issue them.  */
  38 static void (*warn_function) (const char *);
  39
  40 /* Start of data space; can be changed by calling malloc_init.  */
  41 static POINTER data_space_start;
  42
  43 /* Number of bytes of writable memory we can expect to be able to get.  */
  44 static unsigned long lim_data;
  45 \f
  46
  47 #if defined (HAVE_GETRLIMIT) && defined (RLIMIT_AS)
  48 static void
  49 get_lim_data (void)
  50 {
  51   struct rlimit rlimit;
  52
  53   getrlimit (RLIMIT_AS, &rlimit);
  54   if (rlimit.rlim_cur == RLIM_INFINITY)
  55     lim_data = -1;
  56   else
  57     lim_data = rlimit.rlim_cur;
  58 }
  59
  60 #else /* not HAVE_GETRLIMIT */
  61
  62 #ifdef USG
  63
  64 static void
  65 get_lim_data (void)
  66 {
  67   extern long ulimit ();
  68
  69   lim_data = -1;
  70
  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
  75
  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
  81
  82   lim_data -= (long) data_space_start;
  83 }
  84
  85 #else /* not USG */
  86 #ifdef WINDOWSNT
  87
  88 static void
  89 get_lim_data (void)
  90 {
  91   extern unsigned long reserved_heap_size;
  92   lim_data = reserved_heap_size;
  93 }
  94
  95 #else
  96 #if !defined (BSD4_2) && !defined (CYGWIN)
  97
  98 #ifdef MSDOS
  99 void
 100 get_lim_data (void)
 101 {
 102   _go32_dpmi_meminfo info;
 103   unsigned long lim1, lim2;
 104
 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;
 128 }
 129
 130 unsigned long
 131 ret_lim_data (void)
 132 {
 133   get_lim_data ();
 134   return lim_data;
 135 }
 136 #else /* not MSDOS */
 137 static void
 138 get_lim_data (void)
 139 {
 140   lim_data = vlimit (LIM_DATA, -1);
 141 }
 142 #endif /* not MSDOS */
 143
 144 #else /* BSD4_2 || CYGWIN */
 145
 146 static void
 147 get_lim_data (void)
 148 {
 149   struct rlimit XXrlimit;
 150
 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
 157 }
 158 #endif /* BSD4_2 */
 159 #endif /* not WINDOWSNT */
 160 #endif /* not USG */
 161 #endif /* not HAVE_GETRLIMIT */
 162 \f
 163 /* Verify amount of memory available, complaining if we're near the end. */
 164
 165 static void
 166 check_memory_limits (void)
 167 {
 168 #ifdef REL_ALLOC
 169   extern POINTER (*real_morecore) (long);
 170 #endif
 171   extern POINTER (*__morecore) (long);
 172
 173   register POINTER cp;
 174   unsigned long five_percent;
 175   unsigned long data_size;
 176   enum warnlevel new_warnlevel;
 177
 178   if (lim_data == 0)
 179     get_lim_data ();
 180   five_percent = lim_data / 20;
 181
 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;
 190
 191   if (!warn_function)
 192     return;
 193
 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;
 200
 201   /* If we have gone up a level, give the appropriate warning.  */
 202   if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
 203     {
 204       warnlevel = new_warnlevel;
 205       switch (warnlevel)
 206         {
 207         case warned_75:
 208           (*warn_function) ("Warning: past 75% of memory limit");
 209           break;
 210
 211         case warned_85:
 212           (*warn_function) ("Warning: past 85% of memory limit");
 213           break;
 214
 215         case warned_95:
 216           (*warn_function) ("Warning: past 95% of memory limit");
 217         }
 218     }
 219   /* Handle going down in usage levels, with some hysteresis.  */
 220   else
 221     {
 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;
 234     }
 235
 236   if (EXCEEDS_LISP_PTR (cp))
 237     (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
 238 }
 239 \f
 240 #if !defined (CANNOT_DUMP) || !defined (SYSTEM_MALLOC)
 241 /* Some systems that cannot dump also cannot implement these.  */
 242
 243 /*
 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.
 247  *
 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.
 253  *
 254  */
 255
 256 char *
 257 start_of_data (void)
 258 {
 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
 265   /*
 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.
 270    */
 271   extern char **environ;
 272   return ((POINTER) &environ);
 273 #else
 274   extern int data_start;
 275   return ((POINTER) &data_start);
 276 #endif
 277 }
 278 #endif /* (not CANNOT_DUMP or not SYSTEM_MALLOC) */
 279 \f
 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.  */
 283
 284 void
 285 memory_warnings (POINTER start, void (*warnfun) (const char *))
 286 {
 287   extern void (* __after_morecore_hook) (void);     /* From gmalloc.c */
 288
 289   if (start)
 290     data_space_start = start;
 291   else
 292     data_space_start = start_of_data ();
 293
 294   warn_function = warnfun;
 295   __after_morecore_hook = check_memory_limits;
 296
 297   /* Force data limit to be recalculated on each run.  */
 298   lim_data = 0;
 299 }