ip_summed setting for TCP pure-ACK packets

Ben Hutchings
2010-11-08T16:35:17Z

As we discussed at LPC:

Current controllers handled by the sfc driver have a per-queue (rather
than per-packet) option for checksum generation. Currently pure-ACK
packets sent by TCP have ip_summed == CHECKSUM_NONE and we must send
them on hardware queues with checksum generation disabled. To support
this, we allocate 2 hardware queues per core TX queue.

To reduce the risk of reordering (and possibly the number of hardware TX
queues required), it would be helpful for TCP to set ip_summed ==
CHECKSUM_PARTIAL on pure-ACK packets when the output device is known to
support checksum generation.

Ben.

--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.