[Bridge] [PATCH net-next] net: bridge: update multicast stats from maybe_deliver()

Nikolay Aleksandrov nikolay at cumulusnetworks.com
Thu Apr 4 12:06:31 UTC 2019


On 04/04/2019 15:02, Nikolay Aleksandrov wrote:
> On 04/04/2019 14:56, Pablo Neira Ayuso wrote:
>> Simplify this code by updating bridge multicast stats from
>> maybe_deliver().
>>
>> Note that commit 6db6f0eae605 ("bridge: multicast to unicast"), in case
>> the port flag BR_MULTICAST_TO_UNICAST is set, never updates the previous
>> port pointer, therefore it is always going to be different from the
>> existing port in this deduplicated list iteration.
>>
>> Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
>> ---
>>  net/bridge/br_forward.c | 15 ++++-----------
>>  1 file changed, 4 insertions(+), 11 deletions(-)
>>
> 
> This was intentional, the reason I didn't add that call to maybe_deliver() is to avoid
> these checks for the standard unicast fast-path.  We need to avoid touching the mcast
> cache lines (and checks) when using unicast.
> 

To follow-up after my bridge boolean conversion to a flags field in the first cache line
the hit is smaller but it still adds at least 2 new tests in the unicast fast-path which
can easily be avoided.



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