nfp: copy only the relevant part of the TX descriptor for frags
authorJakub Kicinski <jakub.kicinski@netronome.com>
Wed, 28 Nov 2018 06:24:48 +0000 (22:24 -0800)
committerDavid S. Miller <davem@davemloft.net>
Fri, 30 Nov 2018 21:30:44 +0000 (13:30 -0800)
commit95862749674f598e979cb3ef2d18aec2e5d8bd29
treee1332f741a552545059a1d8865f135ce61f243d9
parent6015c71e656bb6895b416c31a8b7db457e45cecf
nfp: copy only the relevant part of the TX descriptor for frags

Chained descriptors for fragments need to duplicate all the descriptor
fields of the skb head, so we copy the descriptor and then modify the
relevant fields.  This is wasteful, because the top half of the descriptor
will get overwritten entirely while the bottom half is not modified at all.
Copy only the bottom half.  This saves us 0.3% of CPU in a GSO test.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/ethernet/netronome/nfp/nfp_net.h
drivers/net/ethernet/netronome/nfp/nfp_net_common.c