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
  37 static enum warnlevel warnlevel;
  38
  39 /* Function to call to issue a warning;
  40    0 means don't issue them.  */
  41 static void (*warn_function) (const char *);
  42
  43 /* Start of data space; can be changed by calling malloc_init.  */
  44 static POINTER data_space_start;
  45
  46 /* Number of bytes of writable memory we can expect to be able to get.  */
  47 static unsigned long lim_data;
  48 \f
  49
  50 #if defined (HAVE_GETRLIMIT) && defined (RLIMIT_AS)
  51 static void
  52 get_lim_data (void)
  53 {
  54   struct rlimit rlimit;
  55
  56   getrlimit (RLIMIT_AS, &rlimit);
  57   if (rlimit.rlim_cur == RLIM_INFINITY)
  58     lim_data = -1;
  59   else
  60     lim_data = rlimit.rlim_cur;
  61 }
  62
  63 #else /* not HAVE_GETRLIMIT */
  64
  65 #ifdef USG
  66
  67 static void
  68 get_lim_data (void)
  69 {
  70   extern long ulimit ();
  71
  72   lim_data = -1;
  73
  74   /* Use the ulimit call, if we seem to have it.  */
  75 #if !defined (ULIMIT_BREAK_VALUE) || defined (GNU_LINUX)
  76   lim_data = ulimit (3, 0);
  77 #endif
  78
  79   /* If that didn't work, just use the macro's value.  */
  80 #ifdef ULIMIT_BREAK_VALUE
  81   if (lim_data == -1)
  82     lim_data = ULIMIT_BREAK_VALUE;
  83 #endif
  84
  85   lim_data -= (long) data_space_start;
  86 }
  87
  88 #else /* not USG */
  89 #ifdef WINDOWSNT
  90
  91 static void
  92 get_lim_data (void)
  93 {
  94   extern unsigned long reserved_heap_size;
  95   lim_data = reserved_heap_size;
  96 }
  97
  98 #else
  99 #if !defined (BSD4_2) && !defined (CYGWIN)
 100
 101 #ifdef MSDOS
 102 void
 103 get_lim_data (void)
 104 {
 105   _go32_dpmi_meminfo info;
 106   unsigned long lim1, lim2;
 107
 108   _go32_dpmi_get_free_memory_information (&info);
 109   /* DPMI server of Windows NT and its descendants reports in
 110      info.available_memory a much lower amount that is really
 111      available, which causes bogus "past 95% of memory limit"
 112      warnings.  Try to overcome that via circumstantial evidence.  */
 113   lim1 = info.available_memory;
 114   lim2 = info.available_physical_pages;
 115   /* DPMI Spec: "Fields that are unavailable will hold -1."  */
 116   if ((long)lim1 == -1L)
 117     lim1 = 0;
 118   if ((long)lim2 == -1L)
 119     lim2 = 0;
 120   else
 121     lim2 *= 4096;
 122   /* Surely, the available memory is at least what we have physically
 123      available, right?  */
 124   if (lim1 >= lim2)
 125     lim_data = lim1;
 126   else
 127     lim_data = lim2;
 128   /* Don't believe they will give us more that 0.5 GB.   */
 129   if (lim_data > 512U * 1024U * 1024U)
 130     lim_data = 512U * 1024U * 1024U;
 131 }
 132
 133 unsigned long
 134 ret_lim_data (void)
 135 {
 136   get_lim_data ();
 137   return lim_data;
 138 }
 139 #else /* not MSDOS */
 140 static void
 141 get_lim_data (void)
 142 {
 143   lim_data = vlimit (LIM_DATA, -1);
 144 }
 145 #endif /* not MSDOS */
 146
 147 #else /* BSD4_2 || CYGWIN */
 148
 149 static void
 150 get_lim_data (void)
 151 {
 152   struct rlimit XXrlimit;
 153
 154   getrlimit (RLIMIT_DATA, &XXrlimit);
 155 #ifdef RLIM_INFINITY
 156   lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
 157 #else
 158   lim_data = XXrlimit.rlim_cur; /* soft limit */
 159 #endif
 160 }
 161 #endif /* BSD4_2 */
 162 #endif /* not WINDOWSNT */
 163 #endif /* not USG */
 164 #endif /* not HAVE_GETRLIMIT */
 165 \f
 166 /* Verify amount of memory available, complaining if we're near the end. */
 167
 168 static void
 169 check_memory_limits (void)
 170 {
 171 #ifdef REL_ALLOC
 172   extern POINTER (*real_morecore) (SIZE);
 173 #endif
 174   extern POINTER (*__morecore) (SIZE);
 175
 176   register POINTER cp;
 177   unsigned long five_percent;
 178   unsigned long data_size;
 179   enum warnlevel new_warnlevel;
 180
 181   if (lim_data == 0)
 182     get_lim_data ();
 183   five_percent = lim_data / 20;
 184
 185   /* Find current end of memory and issue warning if getting near max */
 186 #ifdef REL_ALLOC
 187   if (real_morecore)
 188     cp = (char *) (*real_morecore) (0);
 189   else
 190 #endif
 191   cp = (char *) (*__morecore) (0);
 192   data_size = (char *) cp - (char *) data_space_start;
 193
 194   if (!warn_function)
 195     return;
 196
 197   /* What level of warning does current memory usage demand?  */
 198   new_warnlevel
 199     = (data_size > five_percent * 19) ? warned_95
 200     : (data_size > five_percent * 17) ? warned_85
 201     : (data_size > five_percent * 15) ? warned_75
 202     : not_warned;
 203
 204   /* If we have gone up a level, give the appropriate warning.  */
 205   if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
 206     {
 207       warnlevel = new_warnlevel;
 208       switch (warnlevel)
 209         {
 210         case warned_75:
 211           (*warn_function) ("Warning: past 75% of memory limit");
 212           break;
 213
 214         case warned_85:
 215           (*warn_function) ("Warning: past 85% of memory limit");
 216           break;
 217
 218         case warned_95:
 219           (*warn_function) ("Warning: past 95% of memory limit");
 220         }
 221     }
 222   /* Handle going down in usage levels, with some hysteresis.  */
 223   else
 224     {
 225       /* If we go down below 70% full, issue another 75% warning
 226          when we go up again.  */
 227       if (data_size < five_percent * 14)
 228         warnlevel = not_warned;
 229       /* If we go down below 80% full, issue another 85% warning
 230          when we go up again.  */
 231       else if (warnlevel > warned_75 && data_size < five_percent * 16)
 232         warnlevel = warned_75;
 233       /* If we go down below 90% full, issue another 95% warning
 234          when we go up again.  */
 235       else if (warnlevel > warned_85 && data_size < five_percent * 18)
 236         warnlevel = warned_85;
 237     }
 238
 239   if (EXCEEDS_LISP_PTR (cp))
 240     (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
 241 }
 242 \f
 243 #if !defined(CANNOT_DUMP) || !defined(SYSTEM_MALLOC)
 244 /* Some systems that cannot dump also cannot implement these.  */
 245
 246 /*
 247  *      Return the address of the start of the data segment prior to
 248  *      doing an unexec.  After unexec the return value is undefined.
 249  *      See crt0.c for further information and definition of data_start.
 250  *
 251  *      Apparently, on BSD systems this is etext at startup.  On
 252  *      USG systems (swapping) this is highly mmu dependent and
 253  *      is also dependent on whether or not the program is running
 254  *      with shared text.  Generally there is a (possibly large)
 255  *      gap between end of text and start of data with shared text.
 256  *
 257  */
 258
 259 POINTER
 260 start_of_data (void)
 261 {
 262 #ifdef BSD_SYSTEM
 263   extern char etext;
 264   return (POINTER)(&etext);
 265 #elif defined DATA_START
 266   return ((POINTER) DATA_START);
 267 #elif defined ORDINARY_LINK
 268   /*
 269    * This is a hack.  Since we're not linking crt0.c or pre_crt0.c,
 270    * data_start isn't defined.  We take the address of environ, which
 271    * is known to live at or near the start of the system crt0.c, and
 272    * we don't sweat the handful of bytes that might lose.
 273    */
 274   extern char **environ;
 275   return ((POINTER) &environ);
 276 #else
 277   extern int data_start;
 278   return ((POINTER) &data_start);
 279 #endif
 280 }
 281 #endif /* (not CANNOT_DUMP or not SYSTEM_MALLOC) */
 282 \f
 283 /* Enable memory usage warnings.
 284    START says where the end of pure storage is.
 285    WARNFUN specifies the function to call to issue a warning.  */
 286
 287 void
 288 memory_warnings (POINTER start, void (*warnfun) (const char *))
 289 {
 290   extern void (* __after_morecore_hook) (void);     /* From gmalloc.c */
 291
 292   if (start)
 293     data_space_start = start;
 294   else
 295     data_space_start = start_of_data ();
 296
 297   warn_function = warnfun;
 298   __after_morecore_hook = check_memory_limits;
 299
 300   /* Force data limit to be recalculated on each run.  */
 301   lim_data = 0;
 302 }
 303
 304 /* arch-tag: eab04eda-1f69-447a-8d9f-95f0a3983ca5
 305    (do not change this comment) */