Implemented simple adaptive GC threshold selection.

diff --git a/Zend/zend_gc.c b/Zend/zend_gc.c
index 223dbe6a65cf54dfd7e203160f63aab3b459903e..da9d8b0aefa200979eee9a18060e3485cae8f3c7 100644 (file)
--- a/Zend/zend_gc.c
+++ b/Zend/zend_gc.c
@@ -119,7 +119,6 @@
 #define GC_INVALID           0
 #define GC_FIRST_REAL_ROOT   1
 
-#define GC_DEFAULT_THRESHOLD 10000
 #define GC_DEFAULT_BUF_SIZE  (16 * 1024)
 #define GC_BUF_GROW_STEP     (128 * 1024)
 
@@ -130,6 +129,11 @@
 #define GC_NEED_COMPRESSION(addr) \
        ((GC_COMPRESS_FACTOR > 0) && (addr >= GC_MAX_UNCOMPRESSED))
 
+#define GC_DEFAULT_THRESHOLD 10000
+#define GC_THRESHOLD_STEP    10000
+#define GC_THRESHOLD_MAX     (GC_COMPRESS_FACTOR ? 1000000000 : 1000000)
+#define GC_THRESHOLD_TRIGGER 100
+
 /* GC flags */
 #define GC_HAS_DESTRUCTORS  (1<<0)
 
@@ -485,16 +489,32 @@ static void gc_grow_root_buffer(void)
 
 static void gc_adjust_threshold(int count)
 {
-#if 0
+    uint32_t new_threshold;
+
        /* TODO Very simple heuristic for dynamic GC buffer resizing:
         * If there are "too few" collections, increase the collection threshold
-        * by a factor of two ??? */
-       if (count < 100) {
-               GC_G(gc_threshold) *= 2;
+        * by a fixed step */
+       if (count < GC_THRESHOLD_TRIGGER) {
+               /* increase */
+               if (GC_G(gc_threshold) < GC_THRESHOLD_MAX) {
+                       new_threshold = GC_G(gc_threshold) + GC_THRESHOLD_STEP;
+                       if (new_threshold > GC_THRESHOLD_MAX) {
+                               new_threshold = GC_THRESHOLD_MAX;
+                       }
+                       if (new_threshold > GC_G(buf_size)) {
+                               gc_grow_root_buffer();
+                       }
+                       if (new_threshold <= GC_G(buf_size)) {
+                               GC_G(gc_threshold) = new_threshold;
+                       }
+               }
        } else if (GC_G(gc_threshold) > GC_DEFAULT_THRESHOLD) {
-               GC_G(gc_threshold) /= 2;
+               new_threshold = GC_G(gc_threshold) - GC_THRESHOLD_STEP;
+               if (new_threshold < GC_DEFAULT_THRESHOLD) {
+                       new_threshold = GC_DEFAULT_THRESHOLD;
+               }
+               GC_G(gc_threshold) = new_threshold;
        }
-#endif
 }
 
 static zend_never_inline void ZEND_FASTCALL gc_possible_root_when_full(zend_refcounted *ref)