From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [RFC PATCH] fib_hash: improve route deletion scaling on interface drop with lots of interfaces Date: Tue, 27 Oct 2009 18:01:04 -0700 (PDT) Message-ID: <20091027.180104.135164582.davem@davemloft.net> References: <20091027000302.GA3141@kvack.org> <20091026.171749.106971240.davem@davemloft.net> <20091027142426.GB3141@kvack.org> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: bcrl@lhnet.ca Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:45183 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757078AbZJ1BAk (ORCPT ); Tue, 27 Oct 2009 21:00:40 -0400 In-Reply-To: <20091027142426.GB3141@kvack.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Benjamin LaHaise Date: Tue, 27 Oct 2009 10:24:26 -0400 > On Mon, Oct 26, 2009 at 05:17:49PM -0700, David Miller wrote: >> > bottleneck. Next up in the network code is rt_cache_flush(). Comments? >> >> On a real router adding and removing routes is happening a lot >> whereas interface changes are rare. You're making a more common >> operation more expensive for the sake of a less common one. > > It's not a question of more common vs less common, but if the system can > recover from an adverse event within a reasonable amount of time. Tunnel > flaps occur in the real world, and this results in the change of state of > a large number of interfaces at the same time. Would it be okay if this > is wrapped in a config option? I agree that the extra overhead is not > for everyone. Having it in a config option is worse, distributions are going to turn it on so it would be protecting nothing for %99.999 of folks out there.