~ chicken-core (chicken-5) 4caae1f300fca261443c2c13f37edeed79538ac9
commit 4caae1f300fca261443c2c13f37edeed79538ac9
Author: megane <meganeka@gmail.com>
AuthorDate: Sun Mar 29 10:10:14 2020 +1300
Commit: Peter Bex <peter@more-magic.net>
CommitDate: Mon Apr 13 14:11:48 2020 +0200
Prevent excessive major gcs by preserving a decent amount of unused heap
Signed-off-by: Evan Hanson <evhan@foldling.org>
Signed-off-by: Peter Bex <peter@more-magic.net>
diff --git a/NEWS b/NEWS
index 825fa8ab..6abd273e 100644
--- a/NEWS
+++ b/NEWS
@@ -9,8 +9,12 @@
- Sleeping primordial thread doesn't forget mutations made to
parameters in interrupt handlers anymore. (See #1638. Fix
contributed by Sebastien Marie)
-- A feature corresponding to the word size is available
- regardless of the word size (#1693)
+ - A feature corresponding to the word size is available
+ regardless of the word size (#1693)
+ - A new runtime flag `-:hf' was added, which controls the minimum
+ free heap space at which garbage collector will increase the heap
+ size. This is set to 4M by default to prevent excessive
+ major GCs when the heap hovers around being almost full.
- Build system
- Auto-configure at build time on most platforms. Cross-compilation
diff --git a/manual/Using the compiler b/manual/Using the compiler
index fd656362..7a96920a 100644
--- a/manual/Using the compiler
+++ b/manual/Using the compiler
@@ -223,6 +223,8 @@ by the startup code and will not be contained in the result of
; {{-:hmNUMBER}} : Specifies a maximal heap size (including both semispaces). The default is (2GB - 15).
+; {{-:hfNUMBER}} : Specifies the minimum avilable heap space. If the free space (in one semispace) is less than this number (4MB by default), then the heap is grown.
+
; {{-:hsPERCENTAGE}} : Sets the shrink rate of the heap in percent. The heap is shrunk to {{PERCENTAGE}} when the watermark is reached. The default is 50. Note: If you want to make sure that the heap never shrinks, specify a value of {{0}}. (this can be useful in situations where an optimal heap-size is known in advance).
; {{-:huPERCENTAGE}} : Sets the memory usage watermark below which heap shrinking is triggered. The default is 25.
diff --git a/runtime.c b/runtime.c
index 8e049623..b285b4f2 100644
--- a/runtime.c
+++ b/runtime.c
@@ -163,6 +163,7 @@ static C_TLS int timezone;
#define DEFAULT_HEAP_GROWTH 200
#define DEFAULT_HEAP_SHRINKAGE 50
#define DEFAULT_HEAP_SHRINKAGE_USED 25
+#define DEFAULT_HEAP_MIN_FREE (4 * 1024 * 1024)
#define DEFAULT_FORWARDING_TABLE_SIZE 32
#define DEFAULT_LOCATIVE_TABLE_SIZE 32
#define DEFAULT_COLLECTIBLES_SIZE 1024
@@ -360,6 +361,7 @@ C_TLS C_uword
C_heap_growth = DEFAULT_HEAP_GROWTH,
C_heap_shrinkage = DEFAULT_HEAP_SHRINKAGE,
C_heap_shrinkage_used = DEFAULT_HEAP_SHRINKAGE_USED,
+ C_heap_min_free = DEFAULT_HEAP_MIN_FREE,
C_maximal_heap_size = DEFAULT_MAXIMAL_HEAP_SIZE;
C_TLS time_t
C_startup_time_seconds,
@@ -1362,6 +1364,7 @@ void CHICKEN_parse_command_line(int argc, char *argv[], C_word *heap, C_word *st
" -:o disable stack overflow checks\n"
" -:hiSIZE set initial heap size\n"
" -:hmSIZE set maximal heap size\n"
+ " -:hfSIZE set minimum unused heap size\n"
" -:hgPERCENTAGE set heap growth percentage\n"
" -:hsPERCENTAGE set heap shrink percentage\n"
" -:huPERCENTAGE set percentage of memory used at which heap will be shrunk\n"
@@ -1390,6 +1393,9 @@ void CHICKEN_parse_command_line(int argc, char *argv[], C_word *heap, C_word *st
*heap = arg_val(ptr + 1);
heap_size_changed = 1;
goto next;
+ case 'f':
+ C_heap_min_free = arg_val(ptr + 1);
+ goto next;
case 'g':
C_heap_growth = arg_val(ptr + 1);
goto next;
@@ -3605,7 +3611,7 @@ C_regparm void C_fcall C_reclaim(void *trampoline, C_word c)
/*** isn't gc_mode always GC_MAJOR here? */
/* NOTE: count is actual usage, heap_size is both halves */
if(gc_mode == GC_MAJOR &&
- count < percentage(heap_size/2, C_heap_shrinkage_used) &&
+ C_heap_min_free + count < percentage(heap_size / 2, C_heap_shrinkage_used) &&
C_heap_shrinkage > 0 &&
heap_size > MINIMAL_HEAP_SIZE && !C_heap_size_is_fixed)
C_rereclaim2(percentage(heap_size, C_heap_shrinkage), 0);
@@ -3809,7 +3815,8 @@ C_regparm void C_fcall really_mark(C_word *x)
n = C_header_size(p);
bytes = (h & C_BYTEBLOCK_BIT) ? n : n * sizeof(C_word);
- if(((C_byte *)p2 + bytes + sizeof(C_word)) > tospace_limit) {
+ /* Check for needed size plus minimum unused block: */
+ if(((C_byte *)p2 + bytes + sizeof(C_word) + C_heap_min_free) > tospace_limit) {
/* Detect impossibilities before GC_REALLOC to preserve state: */
if (C_in_stackp((C_word)p) && bytes > stack_size)
panic(C_text("Detected corrupted data in stack"));
Trap