Subject: Re: tainted warnings with tcp splicing in 3.7.1

From: Rick Jones <[email-masked]>
Date: Thu, 10 Jan 2013 10:22:21 -0800

On 01/10/2013 08:20 AM, Eric Dumazet wrote:
> I also want to thanks Rick, as the latest netperf has splice() support.
>
> Thanks Rick !

You are quite welcome - and thank you for helping me get it to actually 
work :)

Those wishing to try it themselves should grab the top-of-trunk netperf 
bits from http://www.netperf.org/svn/netperf2/trunk .  The use of 
splice() is gated by a test-specific -V option:

raj@tardy:~/netperf2_trunk/src$ ./netperf -t omni -- -d recv -V
OMNI Receive TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 
localhost.localdomain () port 0 AF_INET : copy avoidance : demo
Remote      Local       Remote Elapsed Throughput Throughput
Send Socket Recv Socket Send   Time               Units
Size        Size        Size   (sec)
Final       Final
1661688     4194304     16384  10.00   26103.14   10^6bits/s

You should see that "copy avoidance" appearing in the test banner.  It 
will also "take" for things like a migrated TCP_mumble test.  For those 
cases where you don't see a throughput change, enabling CPU utilization 
measurement and looking at that and service demand should show a difference.

happy benchmarking,

rick jones