On 15/08/2017 20:24, Joe Stringer wrote:
On 15 August 2017 at 01:19, Paul Blakey <[email protected]> wrote:
On 15/08/2017 10:28, Paul Blakey wrote:
On 15/08/2017 04:04, Joe Stringer wrote:
On 8 August 2017 at 07:21, Roi Dayan <[email protected]> wrote:
From: Paul Blakey <[email protected]>
Implement support for offloading ovs action set using
tc header rewrite action.
Signed-off-by: Paul Blakey <[email protected]>
Reviewed-by: Roi Dayan <[email protected]>
---
<snip>
@@ -274,6 +346,48 @@ netdev_tc_flow_dump_destroy(struct netdev_flow_dump
*dump)
return 0;
}
+static void
+parse_flower_rewrite_to_netlink_action(struct ofpbuf *buf,
+ struct tc_flower *flower)
+{
+ char *mask = (char *) &flower->rewrite.mask;
+ char *data = (char *) &flower->rewrite.key;
+
+ for (int type = 0; type < ARRAY_SIZE(set_flower_map); type++) {
+ char *put = NULL;
+ size_t nested = 0;
+ int len = ovs_flow_key_attr_lens[type].len;
+
+ if (len <= 0) {
+ continue;
+ }
+
+ for (int j = 0; j < ARRAY_SIZE(set_flower_map[type]); j++) {
+ struct netlink_field *f = &set_flower_map[type][j];
+
+ if (!f->size) {
+ break;
+ }
Seems like maybe there's similar feedback here to the previous patch
wrt sparsely populated array set_flower_map[].
I'll answer there.
Scratch that, I actually meant to write it here.
With this map we have fast (direct lookup) access on the put path
(parse_put_flow_set_masked_action) , and slow access on the reverse dump
path (parse_flower_rewrite_to_netlink_action) which iterates over all
indices, although it should skips them fast if they are empty.
Changing this to sparse map will slow both of the paths, but dumping would
be faster. We didn't write this maps for performance but for convince of
adding new supported attributes.
OK, thanks for the explanation. I figured there must be a reason it
was indexed that way, I just didn't see it in my first review pass
through the series. Obviously fast path should be fast, and typically
we don't worry quite as much about dumping fast (although I have in
the past tested this to determine how many flows we will attempt to
populate in adverse conditions).
What we can do to both maps is:
1) Using ovs thread once, we can create a fast (direct lookup) access map;
for both paths - generating a reverse map at init time and using that
instead for dumping.
Until there's a clear, known advantage I'm not sure if we should do this.
2) Rewrite it in a non sparse way, use it for both.
I think that we generally are more interested in 'put' performance so
if this sacrifices it for 'dump' performance, then it's probably not a
good idea (though it may still be too early to really optimize these).
3) Rewrite it using a switch case, the logic for now is pretty much the same
for all attributes.
What do you think?
Do you think that this third option would improve the readability,
allow more compile-time checking on the code, or more code reuse?
Hi Joe, Thanks for the review,
Since it can be implemented by a map, as with this patch set, all the
switch cases will have the same logic of translating from OVS action set
attributes to flower members, so I think its not much an increase in
readability unless you're looking at a single case.
And regarding compile time checking, we still need to convert from
flower key members to tc action pedit raw offsets/values so we won't
have that there.
I'd like to remove the tc flower struct in the future
and work straight on struct match and actions
so then we will have only the set action to pedit conversion (and one
conversion for all the rest).
I think I'd rather keep the map till it won't fit for the task or we do
the above if that's OK with you.
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