[Qemu-devel] [PATCH 6/6] cache slot lookup

[Glauber Costa <glommer@redhat.com>]

record slot used in last lookup. For the common mmio case,
we'll usually access the same memory slot repeatedly.

Signed-off-by: Glauber Costa <glommer@redhat.com>
---
 kvm-all.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index 85f2922..6a5a98c 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -75,16 +75,25 @@ static KVMSlot *kvm_alloc_slot(KVMState *s)
     return NULL;
 }
 
+static KVMSlot *last_slot = NULL;
+
 static KVMSlot *kvm_lookup_slot(KVMState *s, target_phys_addr_t start_addr)
 {
     int i;
 
+
+    if (last_slot && (start_addr >= last_slot->start_addr &&
+            start_addr < (last_slot->start_addr + last_slot->memory_size)))
+        return last_slot;
+
     for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
         KVMSlot *mem = &s->slots[i];
 
         if (start_addr >= mem->start_addr &&
-            start_addr < (mem->start_addr + mem->memory_size))
+            start_addr < (mem->start_addr + mem->memory_size)) {
+            last_slot = mem;
             return mem;
+        }
     }
 
     return NULL;
-- 
1.5.6.5