degradation in bridging performance of 5% in 2.6.20 when compared to 2.6.19

degradation in bridging performance of 5% in 2.6.20 when compared to 2.6.19

[kalyan tejaswi]

Hi all,
I have been comparing bridging performance for 2.6.20 and 2.6.19
kernels. The kenel configurations are identical for both the kernels.
I use D-Link cards (8139too driver) for the Malta 4Kc board.

The setup is:

netperf  client  <------->  malta 4Kc  <---------> netperf  server.

The throughput statistics (in 10^6 bits/second) are:

                    2.6.19          2.6.20
routing            30.2           30.16
bridging          32.35          30.81

I observe that there has been a degradation in bridging performance of
5% in 2.6.20 when compared to 2.6.19.

Has anyone observed similar behaviour?
Any inputs or suggestions are welcome.


Regards
Kalyan

Re: degradation in bridging performance of 5% in 2.6.20 when compared to 2.6.19

[Rick Jones]

kalyan tejaswi wrote:
> Hi all,
> I have been comparing bridging performance for 2.6.20 and 2.6.19
> kernels. The kenel configurations are identical for both the kernels.
> I use D-Link cards (8139too driver) for the Malta 4Kc board.
> 
> The setup is:
> 
> netperf  client  <------->  malta 4Kc  <---------> netperf  server.
> 
> The throughput statistics (in 10^6 bits/second) are:
> 
>                    2.6.19          2.6.20
> routing            30.2           30.16
> bridging          32.35          30.81
> 
> I observe that there has been a degradation in bridging performance of
> 5% in 2.6.20 when compared to 2.6.19.
> 
> Has anyone observed similar behaviour?
> Any inputs or suggestions are welcome.

In each case is the malta CPU bound?  If not, some idea of the change in 
CPU util might be helpful.

rick jones
btw, netperf 2.4.3 just released:
ftp://ftp.netperf.org/netperf
http://www.netperf.org/svn/netperf2/tags/netperf-2.4.3

Re: degradation in bridging performance of 5% in 2.6.20 when compared to 2.6.19

[Stephen Hemminger]

On Fri, 16 Feb 2007 09:43:20 -0800
Rick Jones <rick.jones2@hp.com> wrote:

> kalyan tejaswi wrote:
> > Hi all,
> > I have been comparing bridging performance for 2.6.20 and 2.6.19
> > kernels. The kenel configurations are identical for both the kernels.
> > I use D-Link cards (8139too driver) for the Malta 4Kc board.
> > 
> > The setup is:
> > 
> > netperf  client  <------->  malta 4Kc  <---------> netperf  server.
> > 
> > The throughput statistics (in 10^6 bits/second) are:
> > 
> >                    2.6.19          2.6.20
> > routing            30.2           30.16
> > bridging          32.35          30.81
> > 
> > I observe that there has been a degradation in bridging performance of
> > 5% in 2.6.20 when compared to 2.6.19.
> > 
> > Has anyone observed similar behaviour?
> > Any inputs or suggestions are welcome.
> 
> In each case is the malta CPU bound?  If not, some idea of the change in 
> CPU util might be helpful.
> 
> rick jones
> btw, netperf 2.4.3 just released:
> ftp://ftp.netperf.org/netperf
> http://www.netperf.org/svn/netperf2/tags/netperf-2.4.3
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I couldn't think of a worse NIC for bridging than the 8139too
because that card has no direct DMA and does a data copy for each receive.

-- 
Stephen Hemminger <shemminger@linux-foundation.org>