From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: cat /proc/net/tcp takes 0.5 seconds on x86_64 Date: Wed, 27 Aug 2008 14:48:00 -0700 Message-ID: <20080827144800.5f9fc5b4@extreme> References: <200808261549.m7QFnVUN032543@bz-web1.app.phx.redhat.com> <20080826163719.GA25066@redhat.com> <87zlmyr5nz.fsf@basil.nowhere.org> <20080827.142941.50104491.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: andi@firstfloor.org, davej@redhat.com, netdev@vger.kernel.org, j.w.r.degoede@hhs.nl To: David Miller Return-path: Received: from mail.vyatta.com ([216.93.170.194]:54283 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752546AbYH0VsC (ORCPT ); Wed, 27 Aug 2008 17:48:02 -0400 In-Reply-To: <20080827.142941.50104491.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 27 Aug 2008 14:29:41 -0700 (PDT) David Miller wrote: > From: Andi Kleen > Date: Wed, 27 Aug 2008 14:41:52 +0200 > > > Dave Jones writes: > > > > > Just had this bug reported against our development tree.. > > > > SUSE had an old patch for this which unfortunately got rejected > > some time ago for some bogus reason. > > Really, your patch fixes this specific slowdown that got introduced > recently? I really doubt it Andi, so please don't use this as an > opportunity to toot your own horn, thanks. > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html I do wonder if having large hash table actually helps? When TCP hash table gets too big, it means every lookup is a cache miss. Assuming a busy server with 2000 connections and perfect hash. On a 4G mem x86-64 we are doing 512K hash entries which is ridiculous. Something like 64K entries is more than enough.