- my proof-of-concept mmapped cache code, currently disabled via ifdef

- also added a cache_profile command, which sorts allocations into
  power-of-2 sizes, then prints out how many are of that size, the
  average amount they use, and the percent of total memory is used.
  Also prints out totally allocated size, number of allocations, and
  average per allocation.

libs/util/zone.c

@@ -38,6 +38,18 @@
 
 #include <stdlib.h>
 
+#undef MMAPPED_CACHE
+#ifdef MMAPPED_CACHE
+# include <unistd.h>
+# include <sys/mman.h>
+# include <sys/types.h>
+# include <sys/stat.h>
+# include <fcntl.h>
+# ifndef _POSIX_MAPPED_FILES
+#  error No _POSIX_MAPPED_FILES?  erk!
+# endif
+#endif
+
 #include "QF/cmd.h"
 #include "QF/console.h"
 #include "QF/cvar.h"
@@ -524,9 +536,11 @@ typedef struct cache_system_s {
 } cache_system_t;
 
 cache_system_t *Cache_TryAlloc (int size, qboolean nobottom);
+void Cache_Profile (void);
 
 cache_system_t cache_head;
 
+#ifndef MMAPPED_CACHE
 void
 Cache_Move (cache_system_t * c)
 {
@@ -548,6 +562,7 @@ Cache_Move (cache_system_t * c)
 		Cache_Free (c->user);			// tough luck...
 	}
 }
+#endif
 
 /*
 	Cache_FreeLow
@@ -557,6 +572,7 @@ Cache_Move (cache_system_t * c)
 void
 Cache_FreeLow (int new_low_hunk)
 {
+#ifndef MMAPPED_CACHE
 	cache_system_t *c;
 
 	while (1) {
@@ -567,6 +583,7 @@ Cache_FreeLow (int new_low_hunk)
 			return;						// there is space to grow the hunk
 		Cache_Move (c);					// reclaim the space
 	}
+#endif
 }
 
 /*
@@ -577,6 +594,7 @@ Cache_FreeLow (int new_low_hunk)
 void
 Cache_FreeHigh (int new_high_hunk)
 {
+#ifndef MMAPPED_CACHE
 	cache_system_t *c, *prev;
 
 	prev = NULL;
@@ -593,6 +611,7 @@ Cache_FreeHigh (int new_high_hunk)
 			prev = c;
 		}
 	}
+#endif
 }
 
 void
@@ -628,6 +647,7 @@ Cache_MakeLRU (cache_system_t * cs)
 cache_system_t *
 Cache_TryAlloc (int size, qboolean nobottom)
 {
+#ifndef MMAPPED_CACHE
 	cache_system_t *cs, *new;
 
 	// is the cache completely empty?
@@ -692,6 +712,29 @@ Cache_TryAlloc (int size, qboolean nobottom)
 	}
 
 	return NULL;						// couldn't allocate
+#else
+	cache_system_t *new;
+	int fd;
+
+	fd = open ("/dev/zero", O_RDWR);
+	if (fd < 0)
+		return NULL;
+	new = mmap (0, size, PROT_READ | PROT_WRITE,
+				MAP_PRIVATE, fd, 0);
+	close (fd);
+	if (new == MAP_FAILED)
+		return NULL;
+
+	new->size = size;
+	new->next = &cache_head;
+	new->prev = cache_head.prev;
+	cache_head.prev->next = new;
+	cache_head.prev = new;
+
+	Cache_MakeLRU (new);
+
+	return new;
+#endif
 }
 
 /*
@@ -736,6 +779,7 @@ Cache_Init (void)
 	cache_head.lru_next = cache_head.lru_prev = &cache_head;
 
 	Cmd_AddCommand ("flush", Cache_Flush, "Clears the current game cache");
+	Cmd_AddCommand ("cache_profile", Cache_Profile, "Prints a profile of the current cache");
 }
 
 /*
@@ -753,6 +797,8 @@ Cache_Free (cache_user_t *c)
 
 	cs = ((cache_system_t *) c->data) - 1;
 
+	Con_DPrintf ("Cache_Free: freeing '%s'\n", cs->name);
+
 	cs->prev->next = cs->next;
 	cs->next->prev = cs->prev;
 	cs->next = cs->prev = NULL;
@@ -760,6 +806,11 @@ Cache_Free (cache_user_t *c)
 	c->data = NULL;
 
 	Cache_UnlinkLRU (cs);
+
+#ifdef MMAPPED_CACHE
+	if (munmap (cs, cs->size))
+		Sys_Error ("Cache_Free: munmap failed!\n");
+#endif
 }
 
 void       *
@@ -811,6 +862,41 @@ Cache_Alloc (cache_user_t *c, int size, const char *name)
 	return Cache_Check (c);
 }
 
+void
+Cache_Profile ()
+{
+	cache_system_t *cs;
+	unsigned int i;
+	unsigned int items[31] = {};
+	unsigned int sizes[31] = {};
+	int count = 0;
+	int total = 0;
+
+	cs = cache_head.next;
+	while (cs != &cache_head) {
+		for (i = 0; (cs->size >> (i + 1)) && i < 30; i++)
+			;
+		items[i]++;
+		sizes[i] += cs->size;
+		total += cs->size;
+		count++;
+		cs = cs->next;
+	}
+	Con_Printf ("Cache Profile:\n");
+	Con_Printf ("%8s  %8s  %8s  %8s  %8s\n",
+				"count", "min", "max", "average", "percent");
+	for (i = 0; i < 31; i++) {
+		if (!items[i])
+			continue;
+		Con_Printf ("%8d  %8d  %8d  %8d  %7d%%\n",
+					items[i], 1 << i, (1 << (i + 1)) - 1,
+					sizes[i] / items[i],
+					(int) (sizes[i] / (float) total * 100));
+	}
+	Con_Printf ("Total allocations: %d in %d allocations, average of"
+				" %d per allocation\n", total, count, total / count);
+}
+
 //============================================================================
 
 void