On Thu, Apr 21, 2016 at 09:02:48AM -0700, Alexander Duyck wrote: > On Thu, Apr 21, 2016 at 12:40 AM, Steffen Klassert > <steffen.klass...@secunet.com> wrote: > > This partly reverts the below mentioned patch because on > > forwarding, such skbs can't be offloaded to a NIC. > > > > We need this to get IPsec GRO for forwarding to work properly, > > otherwise the GRO aggregated packets get segmented again by > > the GSO layer. Although discovered when implementing IPsec GRO, > > this is a general problem in the forwarding path. > > I'm confused as to why you would need this to get IPsec GRO forwarding > to work.
It works without this, but the performance numbers are not that good if we have to do GSO in software. > Are you having to go through a device that doesn't have > NETIF_F_FRAGLIST defined? I don't know of any NIC that can do TSO on a skbuff with fraglist, that's why I try to avoid to have a buffer with fraglist. > Also what is the issue with having to go > through the GSO layer on segmentation? It seems like we might be able > to do something like what we did with GSO partial to split frames so > that they are in chunks that wouldn't require NETIF_F_FRAGLIST. Then > you could get the best of both worlds in that the stack would only > process one super-frame, and the transmitter could TSO a series of > frames that are some fixed MSS in size. This could be interesting. Then we could have a buffer with fraglist, GSO layer splits in skbuffs without fraglist that can be TSO offloaded. Something like this might solve my performance problems.
