Dear Bruce, Thanks for your kind explanation.
I will try to follow your suggestion and see the source code. On Thu, Dec 22, 2016 at 9:25 PM, Bruce Richardson < bruce.richard...@intel.com> wrote: > On Thu, Dec 22, 2016 at 08:48:50PM +0800, Royce Niu wrote: > > But, actually, L3FWD of IP_PIPELINE is also faster than stock L2FWD, > which > > also modifies mac addr. How can explain this? > > > > Actually, I want to know why IP_PIPELINE is much faster and I can learn > > from IP_PIPELINE and make our own program. > > > > But, the documentation of that is not detailed enough. if it is possible, > > could you tell me where is the key to boost? Thanks! > > > > Adding Cristian as IP Pipeline maintainer. > > A lot of tuning work went into IP Pipeline and the table and port > libraries it uses, so I'm not sure that there is just one or two key > changes which give it such good performance. L2 forward just hasn't had > the same level of tuning and, while performing well, is also simplified > to make it understandable as an example. Contrast the code in l2fwd > against equivalent vector code in l3fwd-lpm* files e.g. l3fwd_lpm_sse.h. > The latter is very high performing, the former is more readable. > > Regards, > /Bruce > > > On Thu, Dec 22, 2016 at 7:15 PM, Bruce Richardson < > > bruce.richard...@intel.com> wrote: > > > > > On Thu, Dec 22, 2016 at 12:18:12AM +0800, Royce Niu wrote: > > > > Hi all, > > > > > > > > I tested default L2FWD and IP_PIPELINE (pass-through). The > throughput of > > > > IP_PIPELINE is higher immensely. > > > > > > > > There are only two virtual NICs in KVM. The experiment is just moving > > > > packet from vNIC0 to vNIC1. I think the function is so simple. Why > L2FWD > > > > is much slower? > > > > > > > > How can I improve L2FWD, to make L2FWD faster? > > > > > > > Is IP_PIPELINE in passthrough mode modifying the packets? L2FWD swaps > > > the mac addresses on each packet as it processes them, which can slow > it > > > down. L2FWD is also more an example of how the APIs work than anything > > > else. For fastest possible port-to-port forwarding, testpmd should give > > > the highest performance. > > > > > > /Bruce > > > > > > > > > > > -- > > Regards, > > > > Royce > -- Regards, Royce
