--- libev/ev_linuxaio.c	2019/06/22 22:18:39	1.8
+++ libev/ev_linuxaio.c	2019/06/22 22:29:38	1.9
@@ -44,9 +44,9 @@
 /* we try to fill 4kB pages exactly.
  * the ring buffer header is 32 bytes, every io event is 32 bytes.
  * the kernel takes the io event number, doubles it, adds 2, adds the ring buffer.
- * therefore the calculation below will use "exactly" 8kB for the ring buffer
+ * therefore the calculation below will use "exactly" 4kB for the ring buffer
  */
-#define EV_LINUXAIO_DEPTH (256 / 2 - 2 - 1) /* max. number of io events per batch */
+#define EV_LINUXAIO_DEPTH (128 / 2 - 2 - 1) /* max. number of io events per batch */
 
 /*****************************************************************************/
 /* syscall wrapdadoop */
@@ -207,8 +207,6 @@
 {
   struct aio_ring *ring = (struct aio_ring *)linuxaio_ctx;
 
-  ECB_MEMORY_FENCE_ACQUIRE;
-
   unsigned head = ring->head;
   unsigned tail = *(volatile unsigned *)&ring->tail;
 
@@ -221,6 +219,8 @@
                         || ring->header_length != sizeof (struct aio_ring)) /* TODO: or use it to find io_event[0]? */
     return 0;
 
+  ECB_MEMORY_FENCE_ACQUIRE;
+
   /* parse all available events, but only once, to avoid starvation */
   if (tail > head) /* normal case around */
     linuxaio_parse_events (EV_A_ ring->io_events + head, tail - head);