From 374f2981d1f10bc4307f250f24b2a7ddb9b14be0 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 17 May 2013 12:37:03 +0200
Subject: memory: protect current_map by RCU

Replace the flat_view_mutex with RCU, avoiding futex contention for
dataplane on large systems and many iothreads.

Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/exec/memory.h | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'include')

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 0cd96b1..06ffa1d 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -33,6 +33,7 @@
 #include "qemu/notify.h"
 #include "qapi/error.h"
 #include "qom/object.h"
+#include "qemu/rcu.h"
 
 #define MAX_PHYS_ADDR_SPACE_BITS 62
 #define MAX_PHYS_ADDR            (((hwaddr)1 << MAX_PHYS_ADDR_SPACE_BITS) - 1)
@@ -207,9 +208,13 @@ struct MemoryListener {
  */
 struct AddressSpace {
     /* All fields are private. */
+    struct rcu_head rcu;
     char *name;
     MemoryRegion *root;
+
+    /* Accessed via RCU.  */
     struct FlatView *current_map;
+
     int ioeventfd_nb;
     struct MemoryRegionIoeventfd *ioeventfds;
     struct AddressSpaceDispatch *dispatch;
-- 
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