From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Jones Subject: cat /proc/net/tcp takes 0.5 seconds on x86_64 Date: Tue, 26 Aug 2008 12:37:19 -0400 Message-ID: <20080826163719.GA25066@redhat.com> References: <200808261549.m7QFnVUN032543@bz-web1.app.phx.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: j.w.r.degoede@hhs.nl To: netdev@vger.kernel.org Return-path: Received: from mx2.redhat.com ([66.187.237.31]:54273 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755300AbYHZQir (ORCPT ); Tue, 26 Aug 2008 12:38:47 -0400 Content-Disposition: inline In-Reply-To: <200808261549.m7QFnVUN032543@bz-web1.app.phx.redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: Just had this bug reported against our development tree.. Dave On Tue, Aug 26, 2008 at 11:49:31AM -0400, bugzilla@redhat.com wrote: > Please do not reply directly to this email. All additional > comments should be made in the comments box of this bug. > > https://bugzilla.redhat.com/show_bug.cgi?id=459782 > > Hans de Goede changed: > > What |Removed |Added > ---------------------------------------------------------------------------- > CC| |j.w.r.degoede@hhs.nl > Component|gkrellm |kernel > AssignedTo|j.w.r.degoede@hhs.nl |kernel-maint@redhat.com > Summary|gkrellmd consumes about 75% |cat /proc/net/tcp takes 0.5 > |cpu time |seconds on x86_64, 0.5 > | |seconds !! > > --- Comment #2 from Hans de Goede 2008-08-26 11:49:30 EDT --- > Thanks for reporting this some stracing of gkrellmd has found that reading from > /proc/net/tcp and reading from /proc/net/tcp6 is the culprit, try this on your > x86_64 machine to confirm: > > "time cat /proc/net/tcp" > > To give you an idea on my rawhide x86_64 machine: > [hans@localhost devel]$ time cat /proc/net/tcp > > real 0m0.520s > user 0m0.000s > sys 0m0.446s > > Thats amazingly slow, esp as I only have 8 tcp connections open. > > Some maybe usefull info: top reports a very high load (50%) from soft IRQ's. > > Anyways changing this to a kernel bug. -- http://www.codemonkey.org.uk