commit 2d9aba3961dd6c18cdafecc8ce31b330b45e2723
author Alex Williamson <alex.williamson@hp.com> Fri Jun 05 14:47:13 2009 -0600
committer Mark McLoughlin <markmc@redhat.com> Tue Jun 09 11:38:50 2009 +0100
tree 9cdf576d1579a85d85601d3e10ef92b33ea322ba
parent 8fd2a2f1a9048b9e37a898c2a5e9ef59d0c1a095

virtio-net: MAC filter optimization

The MAC filter table is received from the guest as two separate
buffers, one with unicast entries, the other with multicast
entries.  If we track the index dividing the two sets, we can
avoid searching the part of the table with the wrong type of
entries.

We could store this index as part of the save image, but its
trivially easy to discover it on load.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Mark McLoughlin <markmc@redhat.com>

hw/virtio-net.c

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 8c38454..7863d5d 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -37,6 +37,7 @@
     uint8_t allmulti;
     struct {
         int in_use;
+        int first_multi;
         uint8_t multi_overflow;
         uint8_t uni_overflow;
         uint8_t *macs;
@@ -100,6 +101,7 @@
 
     /* Flush any MAC and VLAN filter table state */
     n->mac_table.in_use = 0;
+    n->mac_table.first_multi = 0;
     n->mac_table.multi_overflow = 0;
     n->mac_table.uni_overflow = 0;
     memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
@@ -172,6 +174,7 @@
         return VIRTIO_NET_ERR;
 
     n->mac_table.in_use = 0;
+    n->mac_table.first_multi = 0;
     n->mac_table.uni_overflow = 0;
     n->mac_table.multi_overflow = 0;
     memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
@@ -190,6 +193,8 @@
         n->mac_table.uni_overflow = 1;
     }
 
+    n->mac_table.first_multi = n->mac_table.in_use;
+
     mac_data.entries = ldl_le_p(elem->out_sg[2].iov_base);
 
     if (sizeof(mac_data.entries) +
@@ -359,17 +364,24 @@
         } else if (n->allmulti || n->mac_table.multi_overflow) {
             return 1;
         }
+
+        for (i = n->mac_table.first_multi; i < n->mac_table.in_use; i++) {
+            if (!memcmp(ptr, &n->mac_table.macs[i * ETH_ALEN], ETH_ALEN)) {
+                return 1;
+            }
+        }
     } else { // unicast
         if (n->mac_table.uni_overflow) {
             return 1;
         } else if (!memcmp(ptr, n->mac, ETH_ALEN)) {
             return 1;
         }
-    }
 
-    for (i = 0; i < n->mac_table.in_use; i++) {
-        if (!memcmp(ptr, &n->mac_table.macs[i * ETH_ALEN], ETH_ALEN))
-            return 1;
+        for (i = 0; i < n->mac_table.first_multi; i++) {
+            if (!memcmp(ptr, &n->mac_table.macs[i * ETH_ALEN], ETH_ALEN)) {
+                return 1;
+            }
+        }
     }
 
     return 0;
@@ -547,6 +559,7 @@
 static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIONet *n = opaque;
+    int i;
 
     if (version_id < 2 || version_id > VIRTIO_NET_VM_VERSION)
         return -EINVAL;
@@ -597,6 +610,14 @@
         n->mac_table.uni_overflow = qemu_get_byte(f);
     }
 
+    /* Find the first multicast entry in the saved MAC filter */
+    for (i = 0; i < n->mac_table.in_use; i++) {
+        if (n->mac_table.macs[i * ETH_ALEN] & 1) {
+            break;
+        }
+    }
+    n->mac_table.first_multi = i;
+
     if (n->tx_timer_active) {
         qemu_mod_timer(n->tx_timer,
                        qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);