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* gc.c (SCM_MTRIGGER_HYSTERESIS): New memory management parameter.

Browse source 
(scm_must_malloc, scm_must_realloc): Added a hysteresis to the
rules for raising scm_mtrigger. Previously, unfortunate but not
unlikely circumstances could result in almost constant invokation
of the gc. Now, this situations should be less likely, but they
are not prevented completely.
This commit is contained in:
Marius Vollmer 1996-12-18 09:42:39 +00:00
parent 016e2ce1d0
commit 6064dcc69e
1 changed files with 20 additions and 4 deletions
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24
libguile/gc.c
View file

@ -95,6 +95,12 @@
* *
* INIT_MALLOC_LIMIT is the initial amount of malloc usage which will * INIT_MALLOC_LIMIT is the initial amount of malloc usage which will
* trigger a GC. * trigger a GC.
*
* SCM_MTRIGGER_HYSTERESIS is the amount of malloc storage that must be
* reclaimed by a GC triggered by must_malloc. If less than this is
* reclaimed, the trigger threshold is raised. [I don't know what a
* good value is. I arbitrarily chose 1/10 of the INIT_MALLOC_LIMIT to
* work around a oscillation that caused almost constant GC.]
*/ */
#define SCM_INIT_HEAP_SIZE (32768L*sizeof(scm_cell)) #define SCM_INIT_HEAP_SIZE (32768L*sizeof(scm_cell))
@ -110,6 +116,7 @@
#endif #endif
#define SCM_EXPHEAP(scm_heap_size) (scm_heap_size*2) #define SCM_EXPHEAP(scm_heap_size) (scm_heap_size*2)
#define SCM_INIT_MALLOC_LIMIT 100000 #define SCM_INIT_MALLOC_LIMIT 100000
#define SCM_MTRIGGER_HYSTERESIS (SCM_INIT_MALLOC_LIMIT/10)
/* CELL_UP and CELL_DN are used by scm_init_heap_seg to find scm_cell aligned inner /* CELL_UP and CELL_DN are used by scm_init_heap_seg to find scm_cell aligned inner
bounds for allocated storage */ bounds for allocated storage */
@ -1405,14 +1412,19 @@ scm_must_malloc (len, what)
return ptr; return ptr;
} }
} }
scm_igc (what); scm_igc (what);
nm = scm_mallocated + size; nm = scm_mallocated + size;
SCM_SYSCALL (ptr = (char *) malloc (size)); SCM_SYSCALL (ptr = (char *) malloc (size));
if (NULL != ptr) if (NULL != ptr)
{ {
scm_mallocated = nm; scm_mallocated = nm;
if (nm > scm_mtrigger) if (nm > scm_mtrigger - SCM_MTRIGGER_HYSTERESIS) {
scm_mtrigger = nm + nm / 2; if (nm > scm_mtrigger)
scm_mtrigger = nm + nm / 2;
else
scm_mtrigger += scm_mtrigger / 2;
}
return ptr; return ptr;
} }
goto malerr; goto malerr;
@ -1450,8 +1462,12 @@ scm_must_realloc (where, olen, len, what)
if (NULL != ptr) if (NULL != ptr)
{ {
scm_mallocated = nm; scm_mallocated = nm;
if (nm > scm_mtrigger) if (nm > scm_mtrigger - SCM_MTRIGGER_HYSTERESIS) {
scm_mtrigger = nm + nm / 2; if (nm > scm_mtrigger)
scm_mtrigger = nm + nm / 2;
else
scm_mtrigger += scm_mtrigger / 2;
}
return ptr; return ptr;
} }
goto ralerr; goto ralerr;