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

[David Miller]

From: Krishna Kumar <krkumar2 at in.ibm.com>
Date: Wed, 08 Aug 2007 15:01:14 +0530

> RESULTS: The performance improvement for TCP No Delay is in the range of -8%
> 	to 320% (with -8% being the sole negative), with many individual tests
> 	giving 50% or more improvement (I think it is to do with the hw slots
> 	getting full quicker resulting in more batching when the queue gets
> 	woken). The results for TCP is in the range of -11% to 93%, with most
> 	of the tests (8/12) giving improvements.

Not because I think it obviates your work, but rather because I'm
curious, could you test a TSO-in-hardware driver converted to
batching and see how TSO alone compares to batching for a pure
TCP workload?

I personally don't think it will help for that case at all as
TSO likely does better job of coalescing the work _and_ reducing
bus traffic as well as work in the TCP stack.