Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965361AbWJBTJE (ORCPT ); Mon, 2 Oct 2006 15:09:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965357AbWJBTJB (ORCPT ); Mon, 2 Oct 2006 15:09:01 -0400 Received: from turing-police.cc.vt.edu ([128.173.14.107]:48085 "EHLO turing-police.cc.vt.edu") by vger.kernel.org with ESMTP id S965355AbWJBTI7 (ORCPT ); Mon, 2 Oct 2006 15:08:59 -0400 Message-Id: <200610021908.k92J8J8c012853@turing-police.cc.vt.edu> X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.2 To: john stultz Cc: tglx@linutronix.de, Andrew Morton , LKML , Ingo Molnar , Jim Gettys , David Woodhouse , Arjan van de Ven , Dave Jones Subject: Re: [patch 00/21] high resolution timers / dynamic ticks - V2 In-Reply-To: Your message of "Mon, 02 Oct 2006 11:38:36 PDT." <1159814317.5873.14.camel@localhost.localdomain> From: Valdis.Kletnieks@vt.edu References: <20061001225720.115967000@cruncher.tec.linutronix.de> <200610021302.k92D23W1003320@turing-police.cc.vt.edu> <1159796582.1386.9.camel@localhost.localdomain> <200610021825.k92IPSnd008215@turing-police.cc.vt.edu> <1159814317.5873.14.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1159816099_5418P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Mon, 02 Oct 2006 15:08:19 -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2015 Lines: 58 --==_Exmh_1159816099_5418P Content-Type: text/plain; charset="us-ascii" Content-Id: <12843.1159816099.1@turing-police.cc.vt.edu> On Mon, 02 Oct 2006 11:38:36 PDT, john stultz said: > Hmmm. So w/ -mm2 we're seeing the TSC get detected as running too slowly > (and its replaced w/ the ACPI PM), but for some reason that doesn't > happen w/ the dynticks patch. It's been switching to ACPI PM for somewhere near forever, I never bothered to check into that because the PM timer provides a reasonably stable clock source (it drifts at about 24 ppm and NTP is happy with it, and I haven't gotten annoyed at the fact the PM timer is slow to read...) I wonder if the TSC has been broken for forever on this box, and I'm just seeing it because dynticks doesn't fall over to PM timer.. > Now, how is cpuspeed changing the cpufreq? Is it using the /sys > interface? I've got hooks in so when the cpufreq changes we should mark > it unstable and fall back to ACPI PM, but maybe I missed whatever hook > cpuspeed is using. Looking at the source, it appears to do this: const char SYSFS_CURRENT_SPEED_FILE[] = "/sys/devices/system/cpu/cpu%u/cpufreq/scaling_setspeed"; // set the current CPU speed void set_speed(unsigned value) { #ifdef DEBUG fprintf(stderr, "[cpu%u] Setting speed to: %uKHz\n", cpu, value); #endif write_line(CURRENT_SPEED_FILE, "%u\n", value); // give CPU / chipset voltage time to settle down usleep(10000); } --==_Exmh_1159816099_5418P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFFIWOjcC3lWbTT17ARAtNXAKC1YfQMlnnHDeu4sGqmzb1fXL5BkwCfd1lu tdtkqfavf307iGWui3gv7aI= =I3Zo -----END PGP SIGNATURE----- --==_Exmh_1159816099_5418P-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/