From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: [PATCH] rfs: Receive Flow Steering Date: Fri, 02 Apr 2010 10:01:42 -0700 Message-ID: <4BB622F6.10606@hp.com> References: <1270193393.1936.52.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Changli Gao , Tom Herbert , davem@davemloft.net, netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from g1t0029.austin.hp.com ([15.216.28.36]:32722 "EHLO g1t0029.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755502Ab0DBRBp (ORCPT ); Fri, 2 Apr 2010 13:01:45 -0400 In-Reply-To: <1270193393.1936.52.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: Eric Dumazet wrote: > > Your claim of RPS being not good for applications is wrong, our test > results show an improvement as is. Maybe your applications dont scale, > because of bad habits, or collidings heuristics, I dont know. The progression in HP-UX was IPS (10.20) (aka RPS) then TOPS (11.0) (aka RFS). We found that IPS was great for single-flow-per-thread-of-execution stuff and that TOPS was better for multiple-flow-per-thread-of-execution stuff. It was long enough ago now that I can safely say for one system-level benchmark not known to be a "networking" benchmark, and without a massive kernel component, TOPS was a 10% win. Not too shabby. It wasn't that IPS wasn't good in its context - just that TOPS was even better. We also preferred the concept of the scheduler giving networking clues as to where to process an application's packets rather than networking trying to tell the scheduler. There was some discussion of out of order worries, but we were willing to trust to the basic soundness of the scheduler - if it was moving threads around willy nilly at a rate able to cause big packet reordering it had fundamental problems that would have to be addressed anyway. And while it may be incindiary to point this out :) I suspect (without concrete data :) that bonding mode 0 is a much, Much, MUCH larger source of out-of-order traffic than any plausible scheduler thrashing. happy benchmarking, rick jones