Messages in this thread | | | Date | Wed, 15 Dec 2010 12:52:02 -0800 | From | John Fastabend <> | Subject | Re: [PATCH 1/3] Kernel interfaces for multiqueue aware socket |
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On 12/15/2010 12:02 PM, Yu, Fenghua wrote: > From: Fenghua Yu <fenghua.yu@intel.com> > > Multiqueue and multicore provide packet parallel processing methodology. > Current kernel and network drivers place one queue on one core. But the higher > level socket doesn't know multiqueue. Current socket only can receive or send > packets through one network interfaces. In some cases e.g. multi bpf filter > tcpdump and snort, a lot of contentions come from socket operations like ring > buffer. Even if the application itself has been fully parallelized and run on > multi-core systems and NIC handlex tx/rx in multiqueue in parallel, network layer > and NIC device driver assemble packets to a single, serialized queue. Thus the > application cannot actually run in parallel in high speed. > > To break the serialized packets assembling bottleneck in kernel, one way is to > allow socket to know multiqueue associated with a NIC interface. So each socket > can handle tx/rx in one queue in parallel. > > Kernel provides several interfaces by which sockets can be bound to rx/tx queues. > User applications can configure socket by providing several sockets that each > bound to a single queue, applications can get data from kernel in parallel. After > that, competitions mentioned above can be removed. > > With this patch, the user-space receiving speed on a Intel SR1690 server with > a single L5640 6-core processor and a single ixgbe-based NIC goes from 0.73Mpps > to 4.20Mpps, nearly a linear speedup. A Intel SR1625 server two E5530 4-core > processors and a single ixgbe-based NIC goes from 0.80Mpps to 4.6Mpps. We noticed > the performance penalty comes from NUMA memory allocation. > > This patch set provides kernel ioctl interfaces for user space. User space can > either directly call the interfaces or libpcap interfaces can be further provided > on the top of the kernel ioctl interfaces. > > The order of tx/rx packets is up to user application. In some cases, e.g. network > monitors, ordering is not a big problem because they more care how to receive and > analyze packets in highest performance in parallel. > > This patch set only implements multiqueue interfaces for AF_PACKET and Intel > ixgbe NIC. Other protocols and NIC's can be handled on the top of this patch set. > > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> > Signed-off-by: Junchang Wang <junchangwang@gmail.com> > Signed-off-by: Xinan Tang <xinan.tang@intel.com> > ---
I think it would be easier to manipulate the sk_hash to accomplish this. Allowing this from user space doesn't seem so great to me. You don't really want to pick the tx/rx bindings for sockets I think what you actually want is to optimize the hashing for this case to avoid the bottleneck you observe.
I'm not too familiar with the af_packet stuff but could you do this with a single flag that indicates the sk_hash should be set in {t}packet_snd(). Maybe I missed your point or there is a reason this wouldn't work. But, then you don't need to do funny stuff in select_queue and it works with rps/xps as well.
--John.
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