Reduce default fiber stack size

8M to 2M on 64-bit, 2M to 1M on 32-bit.

Author: trowski

Zend/zend.c

@@ -180,7 +180,7 @@ static ZEND_INI_MH(OnUpdateFiberStackSize) /* {{{ */
 	if (new_value) {
 		EG(fiber_stack_size) = zend_atol(ZSTR_VAL(new_value), ZSTR_LEN(new_value));
 	} else {
-		EG(fiber_stack_size) = zend_fiber_page_size() * ZEND_FIBER_DEFAULT_PAGE_COUNT;
+		EG(fiber_stack_size) = ZEND_FIBER_DEFAULT_C_STACK_SIZE;
 	}
 	return SUCCESS;
 }

Zend/zend_fibers.c

@@ -106,7 +106,7 @@ static zend_always_inline void zend_observer_fiber_switch_notify(zend_fiber *fro
 }
 /* }}} */
 
-size_t zend_fiber_page_size()
+static size_t zend_fiber_page_size()
 {
 #if _POSIX_MAPPED_FILES
 	static size_t page_size;

Zend/zend_fibers.h

@@ -52,10 +52,6 @@ typedef struct _zend_fiber_context {
 	zend_fiber_stack stack;
 } zend_fiber_context;
 
-#define ZEND_FIBER_GUARD_PAGES 1
-
-#define ZEND_FIBER_DEFAULT_PAGE_COUNT (((sizeof(void *)) < 8) ? 512 : 2048)
-
 typedef struct _zend_fiber {
 	/* Fiber PHP object handle. */
 	zend_object std;
@@ -111,7 +107,9 @@ ZEND_COLD ZEND_NORETURN void zend_error_suspend_fiber(
 ZEND_API void zend_fiber_switch_context(zend_fiber_context *to);
 ZEND_API void zend_fiber_suspend_context(zend_fiber_context *current);
 
-size_t zend_fiber_page_size();
+#define ZEND_FIBER_GUARD_PAGES 1
+
+#define ZEND_FIBER_DEFAULT_C_STACK_SIZE (4096 * (((sizeof(void *)) < 8) ? 256 : 512))
 
 #define ZEND_FIBER_VM_STACK_SIZE (1024 * sizeof(zval))