From: Alex Williamson <alex.williamson@redhat.com>
Date: Fri, 5 Nov 2010 22:01:29 +0000 (-0600)
Subject: apic: Don't iterate past last used apic
X-Git-Tag: v0.14.0-rc0~460
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b538e53ee7e8b9e2920d3286b480276cef209fd4;p=thirdparty%2Fqemu.git

apic: Don't iterate past last used apic

local_apics are allocated sequentially and never removed, so
we can stop any iterations that go to MAX_APICS as soon as we
hit the first NULL.  Looking at a small guest running a virtio-net
workload with oprofile, this drops apic_get_delivery_bitmask()
from #3 in the profile to down in the noise.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---

diff --git a/hw/apic.c b/hw/apic.c
index 63d62c75531..5f4a87c8076 100644
--- a/hw/apic.c
+++ b/hw/apic.c
@@ -437,6 +437,8 @@ static int apic_find_dest(uint8_t dest)
         apic = local_apics[i];
 	if (apic && apic->id == dest)
             return i;
+        if (!apic)
+            break;
     }
 
     return -1;
@@ -472,6 +474,8 @@ static void apic_get_delivery_bitmask(uint32_t *deliver_bitmask,
                         set_bit(deliver_bitmask, i);
                     }
                 }
+            } else {
+                break;
             }
         }
     }