Subject: Re: Re: TSO and IPoIB performance degradation

From: Stephen Hemminger <[email-masked]>
Date: Tue, 7 Mar 2006 13:49:07 -0800

On Tue, 07 Mar 2006 13:44:51 -0800
Matt Leininger <[email-masked]> wrote:

> On Mon, 2006-03-06 at 19:13 -0800, Shirley Ma wrote:
> > 
> > > More likely you are getting hit by the fact that TSO prevents the
> > congestion
> > window from increasing properly. This was fixed in 2.6.15 (around mid
> > of Nov 2005). 
> > 
> > Yep, I noticed the same problem. After updating to the new kernel, the
> > performance are much better, but it's still lower than before.
> 
>  Here is an updated version of OpenIB IPoIB performance for various
> kernels with and without one of the TSO patches.  The netperf
> performance for the latest kernels has not improved the TSO performance
> drop.
> 
>   Any comments or suggestions would be appreciated.
> 
>   - Matt

Configuration information? like did you increase the tcp_rmem, tcp_wmem?
Tcpdump traces of what is being sent and available window?
Is IB using NAPI or just doing netif_rx()?