From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: state of rtcache removal... Date: Wed, 16 Feb 2011 19:27:51 -0800 (PST) Message-ID: <20110216.192751.104051014.davem@davemloft.net> References: <20110216.160838.39164069.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: therbert@google.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:36283 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752546Ab1BQD1Q (ORCPT ); Wed, 16 Feb 2011 22:27:16 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Tom Herbert Date: Wed, 16 Feb 2011 18:59:35 -0800 > On Wed, Feb 16, 2011 at 4:08 PM, David Miller wrote: >> >> So I've been testing out the routing cache removal patch to see >> what the impact is on performance. >> > Interesting results. > > I assume that this test is purposely using sento on a connected socket > to force sendmsg to go through the route lookup :-), so this is > showing what the benefits of rtcache are is when cache hit rate is > 100%. For comparison, it might interesting to see what the > performance is when rate is < 100%. For instance, we often see hit > rates < 20% on front end servers. This could be done flooding to > random addresses in 10/8 or even 0/0... I'm hoping that without the > rtcache performance actually improves in that case! We know that the performance will be higher in the "closer to %0" situation, ie. for DoS workloads. Because all of the route cache management overhead goes away. Anyways I'm working on some ideas to make the high hit rate case perform amicably again.