[win-pv-devel] [PATCH] Reduce xenstore churn

[Owen Smith <owen.smith@xxxxxxxxxx>]

Only write the complete changes to the xenstore MAC address table. There
is no need to write the complete table for each addition or removal,
when additions and removals are processed in a single update.

Pushes the responsibility for writing the MAC table to
FrontendSetMulticastAddresses() once all changes are made, instead of
for each call to MacAddMulticastAddress() or MacRemoveMulticastAddress()

Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
---
 src/xenvif/frontend.c | 7 +++++++
 src/xenvif/mac.c      | 6 +-----
 src/xenvif/mac.h      | 5 +++++
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/xenvif/frontend.c b/src/xenvif/frontend.c
index 3e31654..0ed68df 100644
--- a/src/xenvif/frontend.c
+++ b/src/xenvif/frontend.c
@@ -989,6 +989,7 @@ FrontendSetMulticastAddresses(
     ULONG                   MulticastCount;
     ULONG                   MulticastIndex;
     ULONG                   Index;
+    BOOLEAN                 Change;
     NTSTATUS                status;
 
     Transmitter = FrontendGetTransmitter(Frontend);
@@ -1015,6 +1016,7 @@ FrontendSetMulticastAddresses(
     } else
         MulticastAddress = NULL;
 
+    Change = FALSE;
     for (Index = 0; Index < Count; Index++) {
         BOOLEAN Found;
 
@@ -1042,6 +1044,7 @@ FrontendSetMulticastAddresses(
             (VOID) TransmitterQueueMulticastControl(Transmitter,
                                                     &Address[Index],
                                                     TRUE);
+            Change = TRUE;
         }
     }
 
@@ -1058,11 +1061,15 @@ FrontendSetMulticastAddresses(
                                                 FALSE);
         (VOID) MacRemoveMulticastAddress(Mac,
                                          &MulticastAddress[MulticastIndex]);
+        Change = TRUE;
     }
 
     if (MulticastAddress != NULL)
         __FrontendFree(MulticastAddress);
 
+    if (Change)
+        (VOID) MacDumpAddressTable(Mac);
+
     KeLowerIrql(Irql);
 
     return STATUS_SUCCESS;
diff --git a/src/xenvif/mac.c b/src/xenvif/mac.c
index 0b17a54..19666fe 100644
--- a/src/xenvif/mac.c
+++ b/src/xenvif/mac.c
@@ -295,7 +295,7 @@ __MacReleaseLockShared(
     ExReleaseSpinLockSharedFromDpcLevel(&Mac->Lock);
 }
 
-static NTSTATUS
+NTSTATUS
 MacDumpAddressTable(
     IN  PXENVIF_MAC     Mac
     )
@@ -852,8 +852,6 @@ MacAddMulticastAddress(
     __MacReleaseLockExclusive(Mac);
     KeLowerIrql(Irql);
 
-    (VOID) MacDumpAddressTable(Mac);
-
     Trace("%s: %02X:%02X:%02X:%02X:%02X:%02X\n",
           FrontendGetPrefix(Frontend),
           Address->Byte[0],
@@ -914,8 +912,6 @@ found:
     __MacReleaseLockExclusive(Mac);
     KeLowerIrql(Irql);
 
-    (VOID) MacDumpAddressTable(Mac);
-
     Trace("%s: %02X:%02X:%02X:%02X:%02X:%02X\n",
           FrontendGetPrefix(Frontend),
           Address->Byte[0],
diff --git a/src/xenvif/mac.h b/src/xenvif/mac.h
index 83ce5b8..9340f01 100644
--- a/src/xenvif/mac.h
+++ b/src/xenvif/mac.h
@@ -95,6 +95,11 @@ MacQueryBroadcastAddress(
     OUT PETHERNET_ADDRESS   Address                   
     );
 
+extern NTSTATUS
+MacDumpAddressTable(
+    IN  PXENVIF_MAC     Mac
+    );
+
 extern NTSTATUS
 MacAddMulticastAddress(
     IN      PXENVIF_MAC         Mac,
-- 
2.16.2.windows.1


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