From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luotao Fu Subject: Re: 2.6.24-rc8-rt1: Strange latencies on mpc5200 powerpc - RCU issue? Date: Wed, 30 Jan 2008 12:15:59 +0100 Message-ID: <20080130111559.GC20089@pengutronix.de> References: <47976D06.1010900@grandegger.com> <479DF0A1.3000906@pengutronix.de> <479DF711.5090406@grandegger.com> <479F186A.4020004@pengutronix.de> <479F2C3C.1020203@grandegger.com> <20080130010716.GB16069@linux.vnet.ibm.com> <47A032E9.4080105@grandegger.com> <20080130102255.GA24890@linux.vnet.ibm.com> <47A0552D.20605@grandegger.com> <20080130105715.GE24890@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="pAwQNkOnpTn9IO2O" Cc: Wolfgang Grandegger , Luotao Fu , Steven Rostedt , LKML , RT , Ingo Molnar , Thomas Gleixner To: "Paul E. McKenney" Return-path: Received: from metis.extern.pengutronix.de ([83.236.181.26]:51478 "EHLO metis.extern.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751922AbYA3LQJ (ORCPT ); Wed, 30 Jan 2008 06:16:09 -0500 Content-Disposition: inline In-Reply-To: <20080130105715.GE24890@linux.vnet.ibm.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: --pAwQNkOnpTn9IO2O Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Wed, Jan 30, 2008 at 02:57:16AM -0800, Paul E. McKenney wrote: =2E..... > > Yes, I used "$ cyclictest -n -t1 -p80 -i1000" to measure the latency. So > > far, I have not done other tests. Any recommendation? > > As no-rt load I used "while ls; do ls /bin; done" in one telnet window > > and "while ./hackbench 10; do ./calibrator 400 32M cali; sleep 30; done" > > in another. But already "while ls; do ls /bin; done" is enough to > > trigger the high latencies quickly. Note also, that I work on a root > > files-ystem mounted via NFS resulting in a lot of network traffic and > > utilization. >=20 > I have to ask... >=20 > Did you see large latencies when -not- running on NFS? >=20 I cannot speak for Wolfgang but I myself did not get extraordinary high latencies running tests on system booted from flash. Neither I could produce high latencies on nfs booted system. If my non-rt workload doesn't do heavy filesystem/network accesses. i.E. running only hackbench. Hence we were wondering if the problem is caused by rcu's in network layer or nfs implementation. regards Luotao Fu --=20 Dipl.-Ing. Luotao Fu | Phone: +49-5121-206917-3 Pengutronix - Linux Solutions for Science and Industry Entwicklungszentrum Nord http://www.pengutronix.de --pAwQNkOnpTn9IO2O Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFHoFxviruQY+UyUmERAlp0AJ9DJj0B9iQQYsnIipvswNRRwIqdGQCffvix LW+qOJQP1/d6DHlXijCHNH0= =0GxU -----END PGP SIGNATURE----- --pAwQNkOnpTn9IO2O--