Re: vhost-net patches

[Shirley Ma <mashirle@us.ibm.com>]

Hello Michael,

I am able to get 63xxMb/s throughput with 10% less cpu utilization when
I apply deferring skb patch on top of your most recent vhost patch. The
userspace TCP_STREAM BW used to be 3xxxMb/s from upper stream git tree. 

After applying your recent vhost patch, it goes up to 53xxMb/s. Now it
can reach 63xxMb/s, pretty good news. (this test with transmission
descriptors = 1K)

netperf output with recent vhost patch:

[root@localhost ~]# netperf -H 192.168.122.1 -c -C -l60
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.122.1
(192.168.122.1) 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.    10^6bits/s  % S      % S      us/KB
us/KB

 87380  16384  16384    60.03      5325.82   99.58    83.33    1.532
2.564

netperf output with vhost + deferring skb allocation patch

[root@localhost linux-2.6.32-rc5]# netperf -H 192.168.122.1 -c -C -l60
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.122.1
(192.168.122.1) 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.    10^6bits/s  % S      % S      us/KB
us/KB

 87380  16384  16384    60.02      6332.38   99.33    76.16    1.285
1.970

Thanks
Shirley