On Fri, May 24, 2013 at 2:57 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: > On Fri, 2013-05-24 at 14:23 -0700, Jesse Gross wrote: >> On Fri, May 24, 2013 at 11:58 AM, Eric Dumazet <eric.duma...@gmail.com> >> wrote: >> > On Fri, 2013-05-24 at 10:24 -0700, Jesse Gross wrote: >> > >> >> Does this have any impact on small packets? Those are usually the >> >> common case (i.e. TCP SYN) and I think this is slightly less optimal >> >> for those. >> > >> > No difference at all, small packets are copied anyway in skb->head >> >> Yes, but it makes the Open vSwitch code slightly worse - for example, >> currently checksumming and copying are done in a single step but this >> prevents that. Actually, I'm also curious about the test case that was >> used for large packets and the full profile output since checksumming >> and GSO aren't listed in the one that Thomas gave. >> > > GSO is fully supported in nfnetlink, I see no reason why Open vSwitch > would not allow that.
Offloads are supported. What I want to know is how they affect performance with this change. >> My guess is that there isn't a real different for small packets since >> everything will be in the cache but it seems worth checking given that >> this is optimizing a rare case at the expense of the common one. > > I really doubt checksumming a SYN/ACK packet is that a performance > issue. Do you have performance numbers ? > > You could always provide a patch to restore this copy/checksum if it > really gives a benefit, and if people still use NIC not doing this > checksum. If it makes a difference then it needs to be addressed before this patch goes in since it's the common case. I don't think it will but that's why I'm asking for numbers. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
