Hi Sugesh, I do not have much to add, please see below.
On Thu, Jul 21, 2016 at 11:06:52AM +0000, Chandran, Sugesh wrote: [...] > > > RSS hashing support :- Just to confirm, the RSS flow action allows > > > application to decide the header fields to produce the hash. This > > > gives programmability on load sharing across different queues. The > > > application can program the NIC to calculate the RSS hash only using > > > mac or mac+ ip or ip only using this. > > > > I'd say yes but from your summary, I'm not sure we share the same idea of > > what the RSS action is supposed to do, so here is mine. > > > > Like all flow rules, the pattern part of the RSS action only filters the > > packets > > on which the action will be performed. > > > > The rss_conf parameter (struct rte_eth_rss_conf) only provides a key and a > > RSS hash function to use (ETH_RSS_IPV4, ETH_RSS_NONFRAG_IPV6_UDP, > > etc). > > > > Nothing prevents the RSS hash function from being applied to protocol > > headers which are not necessarily present in the flow rule pattern. These > > are > > two independent things, e.g. you could have a pattern matching IPv4 packets > > yet perform RSS hashing only on UDP headers. > > > > Finally, the RSS action configuration only affects packets coming from this > > flow rule. It is not performed on the device globally so packets which are > > not > > matched are not affected by RSS processing. As a result it might not be > > possible to configure two flow rules specifying incompatible RSS actions > > simultaneously if the underlying device supports only a single global RSS > > context. > > > [Sugesh] thank you for the explanation. This means I can have a rule that > matches on > Every incoming packets(all field wild card rule) and does RSS hash on > selected fields, > MAC only, IP only or IP & MAC? Yes, I guess it could even replace the current method for configuring RSS on a device in a more versatile fashion, but this is a topic for another debate. Let's implement this API first! > This can be useful to do a packet lookup in software by just using > Only hash. Not sure to fully understand your idea, but I'm positive it could be done somehow :) -- Adrien Mazarguil 6WIND
