[openib-general] Heads up on SDP RDMA support for synchronous socket operations

[Michael S. Tsirkin]

Quoting r. Steve Wooding <steve_wooding at keysounds.co.uk>:
> I look forward to trying it out when its ready.

You can now download preliminary patches that add zero-copy RDMA (zcopy)
support for synchronous send operations. The receive side still performs
a copy at this stage.
These patches are not yet intended for trunk inclusion.

Todo:
- implement zero-copy RDMA on the receive side
- bugfixes
- cleanup

Since the receive side does not do zcopy at this stage, for a single connection
this results in a lower bandwidth than without zcopy, but also much lower CPU
utilization on the send size.

Here's an example run:

# ( export SIMPLE_LIBSDP=1;  export LD_PRELOAD=libsdp.so; /usr/local/bin/netperf -H 11.4.8.155 -f M -C -c -- -m 6553600 -M 6553600 )
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 11.4.8.155 (11.4.8.155) port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    MBytes  /s  % S      % S      us/KB   us/KB

124928 124928 6553600    10.00       414.91   2.62     51.36    0.123   2.418

How to use:

svn co https://openib.org/svn/gen2/branches/zcopy/patches

apply patches/send_zcopy.patch and then patches/zcopy1.patch


Thanks,

-- 
MST