Subject: A performance regression of gretap

From: Cong Wang <[email-masked]>
Date: Wed, 10 Jul 2013 06:01:43 -0400 (EDT)

Hi, Pravin

I just noticed the performance over gretap is very bad,
which is probably caused by your GRE refactor patches.

See below:

# netperf -4 -H 192.168.2.1
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.2.1 () port 0 AF_INET
Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

 87380  16384  16384    14.01       0.02   

Could you please take a look? And, gre tunnel is fine, this
problem only exists for gretap. I reviewed the gretap code,
but can't find any bug.

It is very easy to reproduce, just setup a gretap device
on both ends, and run netperf over it.

Thanks!