From owner-freebsd-stable@FreeBSD.ORG Thu Sep 10 13:32:34 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 618651065670; Thu, 10 Sep 2009 13:32:34 +0000 (UTC) (envelope-from doconnor@gsoft.com.au) Received: from cain.gsoft.com.au (cain.gsoft.com.au [203.31.81.10]) by mx1.freebsd.org (Postfix) with ESMTP id AE14A8FC1E; Thu, 10 Sep 2009 13:32:33 +0000 (UTC) Received: from inchoate.gsoft.com.au (ppp121-45-124-246.lns11.adl6.internode.on.net [121.45.124.246]) (authenticated bits=0) by cain.gsoft.com.au (8.13.8/8.13.8) with ESMTP id n8ADWT10087896 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Thu, 10 Sep 2009 23:02:30 +0930 (CST) (envelope-from doconnor@gsoft.com.au) From: "Daniel O'Connor" To: freebsd-stable@freebsd.org Date: Thu, 10 Sep 2009 23:02:19 +0930 User-Agent: KMail/1.9.10 References: <20090906155154.GA8283@onelab2.iet.unipi.it> <20090909203216.GA93761@onelab2.iet.unipi.it> <200909091642.06046.jhb@freebsd.org> In-Reply-To: <200909091642.06046.jhb@freebsd.org> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1480948.AHEMIzcntJ"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200909102302.26318.doconnor@gsoft.com.au> X-Spam-Score: -1.598 () AWL,BAYES_00,RDNS_DYNAMIC X-Scanned-By: MIMEDefang 2.63 on 203.31.81.10 Cc: Luigi Rizzo , John Baldwin Subject: Re: incorrect usleep/select delays with HZ > 2500 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Sep 2009 13:32:34 -0000 --nextPart1480948.AHEMIzcntJ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Thu, 10 Sep 2009, John Baldwin wrote: > > $ARCH/isa/clock.c::DELAY(). I suppose with a few measurements > > at different HZ values and some back of the envelope calculations > > one could even determine estimate the frequency and duration > > of those SMI interrupts! > > On recent motherboards I have seen the SMI# interrupt fire every 250 > ms with execution times ranging from 50 us to 1ms for the legacy USB > interrupt handler. We consistently see the TSC frequency > miscalculated on the motherboards with the 1ms duration interrupt. I > suspect that the clock that drives the periodic SMI# interrupt is > tied to the i8254 meaning that it often fires at the same time that > the i8254 wraps causing the TSC frequency to often be wrong. Can the calculation code disable the SMI# interrupt? Disabling legacy=20 USB could be a problem if you want to use a USB keyboard with the=20 loader (I think). =2D-=20 Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C --nextPart1480948.AHEMIzcntJ Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.12 (FreeBSD) iD8DBQBKqP/q5ZPcIHs/zowRApbKAJ0Y8SHe6RVNNgKBWgeWlQ0MY4L6zACfelI6 ugYVtZytpigqEj9XR/2ICpE= =dhSe -----END PGP SIGNATURE----- --nextPart1480948.AHEMIzcntJ--