Subject: Re: HTB accuracy on 10GbE

From: Eric Dumazet <[email-masked]>
Date: Wed, 04 Nov 2009 06:03:25 +0100

Ryousei Takano a écrit :
> Hi Patrick and Stephen,
> 
> Thanks for your comments.
> 
> I retried on the newer kernel and iproute2, and added the experimental result
> on my page.  Please see 'Experimental result 2':
>     http://code.google.com/p/pspacer/wiki/HTBon10GbE
> 
> The accuracy improves compared with the previous experiment.
> The difference reduces from +810 Mbps to +430 Mbps.
> It is because the timer resolution improves from 1 usec to 1/64 usec.
> But it is not perfect.
> 

Hmm, do you know part of the error comes from the user tool itself ?

If you check iperf results at sender and receiver you'll see different
values, sender lies a bit.

Tried here on a Gbit link (I dont have 10Gbe yet)

$ ./iperf.bench.sh
.100 104
.200 206
.300 307
.400 413
.500 515
.600 610
.700 715
.800 822
.900 913
1.000 945

while on receiver :
[  4]  0.0- 5.3 sec  62.8 MBytes    100 Mbits/sec
[  5]  0.0- 5.1 sec    123 MBytes    202 Mbits/sec
[  4]  0.0- 5.1 sec    183 MBytes    303 Mbits/sec
[  5]  0.0- 5.1 sec    246 MBytes    409 Mbits/sec
[  4]  0.0- 5.0 sec    307 MBytes    511 Mbits/sec
[  5]  0.0- 5.0 sec    364 MBytes    607 Mbits/sec
[  4]  0.0- 5.0 sec    427 MBytes    711 Mbits/sec
[  5]  0.0- 5.0 sec    490 MBytes    818 Mbits/sec
[  4]  0.0- 5.0 sec    545 MBytes    909 Mbits/sec
[  5]  0.0- 5.0 sec    565 MBytes    941 Mbits/sec

You might use longer intervals to reduce this error (10 secs instead of 5 secs)

$./iperf.bench.sh
.100 102
.200 204
.300 305
.400 410
.500 513
.600 608
.700 713
.800 820
.900 911
1.000 943