> > > >> On 3/22/2019 11:57 AM, Jakub Grajciar wrote: > >>> Memory interface (memif), provides high performance packet transfer > >>> over shared memory. > >>> > >>> Signed-off-by: Jakub Grajciar <jgraj...@cisco.com> > >> > > > > <...> > > > >> With that in mind, I believe that 23Mpps is fine performance. No > >> performance target is > >> defined, the goal is to be as fast as possible. > > Use of C11 atomics have proven to provide better performance on weakly > ordered architectures (at least on Arm). IMO, C11 atomics should be used to > implement the fast path functions at least. This ensures optimal performance > on all supported architectures in DPDK. > > > > Atomics are not required by memif driver. > > Correct, only thing we need is store barrier once per batch of packets, to > make sure that descriptor changes are globally visible before we bump head > pointer. May be I was not clear in my comments, I meant that the use of GCC C++11 memory model aware atomic operations [1] show better performance. So, instead of using full memory barriers you can use store-release and load-acquire semantics. A similar change was done to svm_fifo data structure in VPP [2] (though the original algorithm used was different from the one used in this memif patch).
[1] https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html [2] https://gerrit.fd.io/r/#/c/18223/ > > -- > Damjan
