[ovs-dev] [PATCH V7 2/2] odp-util: Do not rewrite fields with the same values as matched

[Ben Pfaff]

On Thu, Mar 21, 2019 at 07:44:16AM +0000, Eli Britstein wrote:
> To improve performance and avoid wasting resources for HW offloaded
> flows, do not rewrite fields that are matched with the same value.
> 
> Signed-off-by: Eli Britstein <elibr at mellanox.com>
> Reviewed-by: Roi Dayan <roid at mellanox.com>

Thanks.  I applied this series to master.

I folded in an improvement to the comment on keycmp_mask() and minor
style fixes to the same function:

diff --git a/lib/odp-util.c b/lib/odp-util.c
index 291c05f84a48..b6552c5c208a 100644
--- a/lib/odp-util.c
+++ b/lib/odp-util.c
@@ -7367,29 +7367,27 @@ struct offsetof_sizeof {
     int size;
 };
 
-/* Compare the keys similary to memcmp, but each field separately.
- * The offsets and sizes of each field is provided by offsetof_sizeof_arr
- * argument.
- * For fields with the same value, zero out their mask part in order not to
- * rewrite them as it's unnecessary */
+/* Compares each of the fields in 'key0' and 'key1'.  The fields are specified
+ * in 'offsetof_sizeof_arr', which is an array terminated by a 0-size field.
+ * Returns true if all of the fields are equal, false if at least one differs.
+ * As a side effect, for each field that is the same in 'key0' and 'key1',
+ * zeros the corresponding bytes in 'mask'. */
 static bool
 keycmp_mask(const void *key0, const void *key1,
             struct offsetof_sizeof *offsetof_sizeof_arr, void *mask)
 {
-    int field;
     bool differ = false;
 
-    for (field = 0 ; ; field++) {
+    for (int field = 0 ; ; field++) {
         int size = offsetof_sizeof_arr[field].size;
         int offset = offsetof_sizeof_arr[field].offset;
-        char *pkey0 = ((char *)key0) + offset;
-        char *pkey1 = ((char *)key1) + offset;
-        char *pmask = ((char *)mask) + offset;
-
         if (size == 0) {
             break;
         }
 
+        char *pkey0 = ((char *)key0) + offset;
+        char *pkey1 = ((char *)key1) + offset;
+        char *pmask = ((char *)mask) + offset;
         if (memcmp(pkey0, pkey1, size) == 0) {
             memset(pmask, 0, size);
         } else {