Subject: [ofa-general] Re: [PATCH 0/9 Rev3] Implement batching skb API and support in IPoIB

From: jamal <[email-masked]>
Date: Thu, 23 Aug 2007 18:04:10 -0400

On Wed, 2007-22-08 at 13:21 -0700, David Miller wrote:
> From: Rick Jones <[email-masked]>
> Date: Wed, 22 Aug 2007 10:09:37 -0700
> 
> > Should it be any more or less worrysome than small packet
> > performance (eg the TCP_RR stuff I posted recently) being rather
> > worse with TSO enabled than with it disabled?
> 
> That, like any such thing shown by the batching changes, is a bug
> to fix.

Possibly a bug - but you really should turn off TSO if you are doing
huge interactive transactions (which is fair because there is a clear
demarcation).
The litmus test is the same as any change that is supposed to improve
net performance - it has to demonstrate it is not intrusive and that it
improves (consistently) performance. The standard metrics are
{throughput, cpu-utilization, latency} i.e as long as one improves and
others remain zero, it would make sense. Yes, i am religious for
batching after all the invested sweat (and i continue to work on it
hoping to demystify) - the theory makes a lot of sense.
 
cheers,
jamal