From owner-freebsd-hackers Wed Feb 27 17:57: 4 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from peitho.fxp.org (peitho.fxp.org [209.26.95.40]) by hub.freebsd.org (Postfix) with ESMTP id 9EBF737B41B; Wed, 27 Feb 2002 17:56:53 -0800 (PST) Received: by peitho.fxp.org (Postfix, from userid 1501) id D4AC11366A; Wed, 27 Feb 2002 20:56:51 -0500 (EST) Date: Wed, 27 Feb 2002 20:56:51 -0500 From: Chris Faulhaber To: "Frost, Stephen C" Cc: "'freebsd-questions@freebsd.org'" , "'freebsd-hackers@freebsd.org'" Subject: Re: FreeBSD, SMP and Performance Speeds? Message-ID: <20020228015651.GA90541@peitho.fxp.org> Mail-Followup-To: Chris Faulhaber , "Frost, Stephen C" , "'freebsd-questions@freebsd.org'" , "'freebsd-hackers@freebsd.org'" References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="AhhlLboLdkugWU4S" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.24i Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG --AhhlLboLdkugWU4S Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 27, 2002 at 04:26:35PM -0800, Frost, Stephen C wrote: >=20 > All - >=20 > I have RTFM'd, with little luck. Can some enlightened soul impart knowle= dge > upon me, thus letting me know why any kernels compiled with SMP enabled s= eem > to be slowing the whole system down? Throughput goes down by 40%. Tasks > take twice as long to run, etc, etc... >=20 > I have multiple boxes (Dells, IBM's, Microns, Gateways...) running FreeBSd > 4.5, all showing the same phenomenon. I initially mistook it for a NIC > driver issue, but it appears to be system-wide. And is directly linked to > SMP: two kernels, identical EXCEPT that one has SMP enabled, the other no= t. > The enabled kernel that *should* be fully utilizing multi-procs is sudden= ly > effectively running at half speed. >=20 > Is this a config issue? Any helpful hints? Or is it better just to keep > SMP disabled on a multi-proc box? >=20 Is this an old Pentium? If so, update to a recent -stable; a fix was committed a few weeks ago fixing a problem where the caches on both processors were not enabled on Pentiums. Otherwise, we have a few PII and PIII boxes here that work quite under 4.5. (oh, you might want to try the freebsd-smp list) --=20 Chris D. Faulhaber - jedgar@fxp.org - jedgar@FreeBSD.org -------------------------------------------------------- FreeBSD: The Power To Serve - http://www.FreeBSD.org --AhhlLboLdkugWU4S Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (FreeBSD) Comment: FreeBSD: The Power To Serve iEYEARECAAYFAjx9jmMACgkQObaG4P6BelBnuwCffzjYbdp6FfLmNLh6QNVhusDm 8TkAoIEBY2wUrKbp6/diZPD0FHjVmXCW =xlGF -----END PGP SIGNATURE----- --AhhlLboLdkugWU4S-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message