#include <stdio.h>
#include <errno.h>
#include <string.h>
+#include <math.h>
#ifdef __ia64__
#include <ucontext.h>
*/
int scm_debug_cells_gc_interval = 0;
+#if SCM_ENABLE_DEPRECATED == 1
/* Hash table that keeps a reference to objects the user wants to protect from
garbage collection. It could arguably be private but applications have come
to rely on it (e.g., Lilypond 2.13.9). */
SCM scm_protects;
-
+#else
+static SCM scm_protects;
+#endif
#if (SCM_DEBUG_CELL_ACCESSES == 1)
#endif /* SCM_DEBUG_CELL_ACCESSES == 1 */
\f
+
+/* Compatibility. */
+
+#ifndef HAVE_GC_GET_HEAP_USAGE_SAFE
+static void
+GC_get_heap_usage_safe (GC_word *pheap_size, GC_word *pfree_bytes,
+ GC_word *punmapped_bytes, GC_word *pbytes_since_gc,
+ GC_word *ptotal_bytes)
+{
+ *pheap_size = GC_get_heap_size ();
+ *pfree_bytes = GC_get_free_bytes ();
+ *punmapped_bytes = GC_get_unmapped_bytes ();
+ *pbytes_since_gc = GC_get_bytes_since_gc ();
+ *ptotal_bytes = GC_get_total_bytes ();
+}
+#endif
+
+#ifndef HAVE_GC_GET_FREE_SPACE_DIVISOR
+static GC_word
+GC_get_free_space_divisor (void)
+{
+ return GC_free_space_divisor;
+}
+#endif
+
+\f
/* Hooks. */
scm_t_c_hook scm_before_gc_c_hook;
scm_t_c_hook scm_before_mark_c_hook;
static long gc_time_taken = 0;
static long gc_start_time = 0;
+static unsigned long free_space_divisor;
+static unsigned long minimum_free_space_divisor;
+static double target_free_space_divisor;
static unsigned long protected_obj_count = 0;
SCM_SYMBOL (sym_times, "gc-times");
-/* Number of calls to SCM_NEWCELL since startup. */
-unsigned scm_newcell_count;
-unsigned scm_newcell2_count;
-
-
/* {Scheme Interface to GC}
*/
static SCM
#define FUNC_NAME s_scm_gc_stats
{
SCM answer;
- size_t heap_size, free_bytes, bytes_since_gc, total_bytes;
+ GC_word heap_size, free_bytes, unmapped_bytes, bytes_since_gc, total_bytes;
size_t gc_times;
- heap_size = GC_get_heap_size ();
- free_bytes = GC_get_free_bytes ();
- bytes_since_gc = GC_get_bytes_since_gc ();
- total_bytes = GC_get_total_bytes ();
- gc_times = GC_gc_no;
+ GC_get_heap_usage_safe (&heap_size, &free_bytes, &unmapped_bytes,
+ &bytes_since_gc, &total_bytes);
+ gc_times = GC_gc_no;
answer =
scm_list_n (scm_cons (sym_gc_time_taken, scm_from_long (gc_time_taken)),
scm_storage_prehistory ()
{
GC_all_interior_pointers = 0;
- GC_set_free_space_divisor (scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3));
+ free_space_divisor = scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3);
+ minimum_free_space_divisor = free_space_divisor;
+ target_free_space_divisor = free_space_divisor;
+ GC_set_free_space_divisor (free_space_divisor);
GC_INIT ();
void *data SCM_UNUSED)
{
if (gc_start_time)
- { long now = scm_c_get_internal_run_time ();
+ {
+ long now = scm_c_get_internal_run_time ();
gc_time_taken += now - gc_start_time;
gc_start_time = 0;
}
return NULL;
}
+/* Return some idea of the memory footprint of a process, in bytes.
+ Currently only works on Linux systems. */
+static size_t
+get_image_size (void)
+{
+ unsigned long size, resident, share;
+ size_t ret = 0;
+
+ FILE *fp = fopen ("/proc/self/statm", "r");
+
+ if (fp && fscanf (fp, "%lu %lu %lu", &size, &resident, &share) == 3)
+ ret = resident * 4096;
+
+ if (fp)
+ fclose (fp);
+
+ return ret;
+}
+
+/* Make GC run more frequently when the process image size is growing,
+ measured against the number of bytes allocated through the GC.
+
+ If Guile is allocating at a GC-managed heap size H, libgc will tend
+ to limit the process image size to H*N. But if at the same time the
+ user program is mallocating at a rate M bytes per GC-allocated byte,
+ then the process stabilizes at H*N*M -- assuming that collecting data
+ will result in malloc'd data being freed. It doesn't take a very
+ large M for this to be a bad situation. To limit the image size,
+ Guile should GC more often -- the bigger the M, the more often.
+
+ Numeric functions that produce bigger and bigger integers are
+ pessimal, because M is an increasing function of time. Here is an
+ example of such a function:
+
+ (define (factorial n)
+ (define (fac n acc)
+ (if (<= n 1)
+ acc
+ (fac (1- n) (* n acc))))
+ (fac n 1))
+
+ It is possible for a process to grow for reasons that will not be
+ solved by faster GC. In that case M will be estimated as
+ artificially high for a while, and so GC will happen more often on
+ the Guile side. But when it stabilizes, Guile can ease back the GC
+ frequency.
+
+ The key is to measure process image growth, not mallocation rate.
+ For maximum effectiveness, Guile reacts quickly to process growth,
+ and exponentially backs down when the process stops growing.
+
+ See http://thread.gmane.org/gmane.lisp.guile.devel/12552/focus=12936
+ for further discussion.
+ */
+static void *
+adjust_gc_frequency (void * hook_data SCM_UNUSED,
+ void *fn_data SCM_UNUSED,
+ void *data SCM_UNUSED)
+{
+ static size_t prev_image_size = 0;
+ static size_t prev_bytes_alloced = 0;
+ size_t image_size;
+ size_t bytes_alloced;
+
+ image_size = get_image_size ();
+ bytes_alloced = GC_get_total_bytes ();
+
+#define HEURISTICS_DEBUG 0
+
+#if HEURISTICS_DEBUG
+ fprintf (stderr, "prev image / alloced: %lu / %lu\n", prev_image_size, prev_bytes_alloced);
+ fprintf (stderr, " image / alloced: %lu / %lu\n", image_size, bytes_alloced);
+ fprintf (stderr, "divisor %lu / %f\n", free_space_divisor, target_free_space_divisor);
+#endif
+
+ if (prev_image_size && bytes_alloced != prev_bytes_alloced)
+ {
+ double growth_rate, new_target_free_space_divisor;
+ double decay_factor = 0.5;
+ double hysteresis = 0.1;
+
+ growth_rate = ((double) image_size - prev_image_size)
+ / ((double)bytes_alloced - prev_bytes_alloced);
+
+#if HEURISTICS_DEBUG
+ fprintf (stderr, "growth rate %f\n", growth_rate);
+#endif
+
+ new_target_free_space_divisor = minimum_free_space_divisor;
+
+ if (growth_rate > 0)
+ new_target_free_space_divisor *= 1.0 + growth_rate;
+
+#if HEURISTICS_DEBUG
+ fprintf (stderr, "new divisor %f\n", new_target_free_space_divisor);
+#endif
+
+ if (new_target_free_space_divisor < target_free_space_divisor)
+ /* Decay down. */
+ target_free_space_divisor =
+ (decay_factor * target_free_space_divisor
+ + (1.0 - decay_factor) * new_target_free_space_divisor);
+ else
+ /* Jump up. */
+ target_free_space_divisor = new_target_free_space_divisor;
+
+#if HEURISTICS_DEBUG
+ fprintf (stderr, "new target divisor %f\n", target_free_space_divisor);
+#endif
+
+ if (free_space_divisor + 0.5 + hysteresis < target_free_space_divisor
+ || free_space_divisor - 0.5 - hysteresis > target_free_space_divisor)
+ {
+ free_space_divisor = lround (target_free_space_divisor);
+#if HEURISTICS_DEBUG
+ fprintf (stderr, "new divisor %lu\n", free_space_divisor);
+#endif
+ GC_set_free_space_divisor (free_space_divisor);
+ }
+ }
+
+ prev_image_size = image_size;
+ prev_bytes_alloced = bytes_alloced;
+
+ return NULL;
+}
+
\f
char const *
scm_i_tag_name (scm_t_bits tag)
{
- if (tag >= 255)
- {
- int k = 0xff & (tag >> 8);
- return (scm_smobs[k].name);
- }
-
- switch (tag) /* 7 bits */
+ switch (tag & 0x7f) /* 7 bits */
{
case scm_tcs_struct:
return "struct";
return "port";
break;
case scm_tc7_smob:
- return "smob"; /* should not occur. */
+ {
+ int k = 0xff & (tag >> 8);
+ return (scm_smobs[k].name);
+ }
break;
}
scm_c_hook_add (&scm_before_gc_c_hook, queue_after_gc_hook, NULL, 0);
scm_c_hook_add (&scm_before_gc_c_hook, start_gc_timer, NULL, 0);
scm_c_hook_add (&scm_after_gc_c_hook, accumulate_gc_timer, NULL, 0);
+ scm_c_hook_add (&scm_after_gc_c_hook, adjust_gc_frequency, NULL, 0);
#ifdef HAVE_GC_SET_START_CALLBACK
GC_set_start_callback (run_before_gc_c_hook);
HCoop / bpt / guile.git / blobdiff