better defaults and debugging for fixed size chunks

benchmarks/gabriel/difftimes.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+# set -ex
+
+BENCHDIR=$(dirname $0)
+if [ "${BENCHDIR%%/*}" = "." ]; then
+    BENCHDIR="$(pwd)${BENCHDIR#.}"
+fi
+
+TS1="${1:--2}"
+TS2="${2:--1}"
+DB="${3:-${BENCHDIR}/times.tsv}"
+
+if [ "$TS1" -lt 1000000000 ]; then
+    TS1=$(cut -f 7 "$DB" | sort -nru | tail -n +$((0 - TS1)) | head -1)
+fi
+if [ "$TS2" -lt 1000000000 ]; then
+    TS2=$(cut -f 7 "$DB" | sort -nru | tail -n +$((0 - TS2)) | head -1)
+fi
+
+join -t $'\t' \
+     <(grep $'\t'"$TS1"$'\t' "$DB" | cut -f 1-2) \
+     <(grep $'\t'"$TS2"$'\t' "$DB" | cut -f 1-2) \
+    | perl -F'\t' -ane '$g=($F[1]<=0)?0:100*($F[2]-$F[1])/$F[1]; printf STDOUT "%s\t%d\t%d\t%.2f%%\n", @F, $g'

gc.c

@@ -45,6 +45,22 @@ static size_t sexp_heap_total_size (sexp_heap h) {
 }
 
 #if ! SEXP_USE_GLOBAL_HEAP
+#if SEXP_USE_DEBUG_GC
+void sexp_debug_heap_stats (sexp_heap heap) {
+  sexp_free_list ls;
+  size_t available = 0;
+  for (ls=heap->free_list; ls; ls=ls->next)
+    available += ls->size;
+#if SEXP_USE_FIXED_CHUNK_SIZE_HEAPS
+  sexp_debug_printf("free heap: %p (chunk size: %lu): %ld / %ld used (%.2f%%)", heap, heap->chunk_size, heap->size - available, heap->size, 100*(heap->size - available) / (float)heap->size);
+#else
+  sexp_debug_printf("free heap: %p: %ld / %ld used (%.2f%%)", heap, heap->size - available, heap->size, 100*(heap->size - available) / (float)heap->size);
+#endif
+  if (heap->next)
+    sexp_debug_heap_stats(heap->next);
+}
+#endif
+
 void sexp_free_heap (sexp_heap heap) {
 #if SEXP_USE_MMAP_GC
   munmap(heap, sexp_heap_pad_size(heap->size));
@@ -618,4 +634,4 @@ void sexp_gc_init (void) {
 #endif
 }
 
-#endif
+#endif  /* ! SEXP_USE_BOEHM && ! SEXP_USE_MALLOC */

include/chibi/sexp.h

@@ -1760,9 +1760,11 @@ SEXP_API sexp sexp_finalize (sexp ctx);
 
 #if SEXP_USE_GLOBAL_HEAP
 #define sexp_free_heap(heap)
+#define sexp_debug_heap_stats(heap)
 #define sexp_destroy_context(ctx) SEXP_TRUE
 #else
 SEXP_API void sexp_free_heap (sexp_heap heap);
+SEXP_API void sexp_debug_heap_stats (sexp_heap heap);
 SEXP_API sexp sexp_destroy_context (sexp ctx);
 SEXP_API sexp sexp_copy_context (sexp ctx, sexp dst, sexp flags);
 #endif

sexp.c

@@ -617,8 +617,16 @@ sexp sexp_bootstrap_context (sexp_uint_t size, sexp_uint_t max_size) {
   } else {
     sexp_context_heap(ctx) = heap;
 #if SEXP_USE_FIXED_CHUNK_SIZE_HEAPS
-    heap->chunk_size = 1<<(4+SEXP_64_BIT);
+    heap->chunk_size = sexp_heap_align(1);
-    sexp_grow_heap(ctx, sexp_heap_align(size), 0);
+    heap->next = sexp_make_heap(size, max_size, 0);
+    if (heap->next) {
+      heap->next->chunk_size = sexp_heap_align(1 + sexp_heap_align(1));
+      heap->next->next = sexp_make_heap(size, max_size, 0);
+      if (heap->next->next) {
+        heap->next->next->chunk_size = sexp_heap_align(1 + sexp_heap_align(1 + sexp_heap_align(1)));
+        heap->next->next->next = sexp_make_heap(size, max_size, 0);
+      }
+    }
 #endif
   }
   return ctx;
@@ -677,6 +685,9 @@ sexp sexp_destroy_context (sexp ctx) {
   size_t sum_freed;
   if (sexp_context_heap(ctx)) {
     heap = sexp_context_heap(ctx);
+#if SEXP_USE_DEBUG_GC
+    sexp_debug_heap_stats(heap);
+#endif
     sexp_markedp(ctx) = 1;
     sexp_markedp(sexp_context_globals(ctx)) = 1;
     sexp_mark(ctx, sexp_global(ctx, SEXP_G_TYPES));