[ovs-dev] [PATCH 3/3] classifier: Speed up lookup when metadata partitions the flow table.

[Rajahalme, Jarno (NSN - FI/Espoo)]

On May 8, 2013, at 11:13 , ext Rajahalme, Jarno (NSN - FI/Espoo) wrote:
>> 
>>    old_rule = insert_rule(cls, table, rule);
>>    if (!old_rule) {
>> +        if (minimask_get_metadata_mask(&rule->match.mask) == OVS_BE64_MAX) {
>> +            ovs_be64 metadata = miniflow_get_metadata(&rule->match.flow);
>> +            rule->partition = create_partition(cls, table, metadata);
> 
> I guess that Andy's comment on masked metadata support would be a generalization to this, where the metadata mask would be made part of the cls_partition, and the hmap would be keyed by the combination of the (masked) metadata and the mask. It would be pretty straightforward, but would be a bit more work. With this generalization this part would look like something like this:
> 
>            ovs_be64 metadata_mask = minimask_get_metadata_mask(&rule->match.mask);
>            if (metadata_mask) {
>                ovs_be64 metadata = miniflow_get_metadata(&rule->match.flow);
>                rule->partition = create_partition(cls, table, metadata, metadata_mask);
> 
> Corresponding changes would be needed elsewhere.
> 
> I have no idea of the performance impact, though.
> 

Just came to think that on lookup this would need a separate find_partition() call for each table (with the table's metadata mask), which would not be very efficient. So, unless there is a use case that would benefit from the masked metadata partitioning, it likely would not be worth the additional cost.

  Jarno