From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760012AbYEHOFZ (ORCPT ); Thu, 8 May 2008 10:05:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752759AbYEHOFJ (ORCPT ); Thu, 8 May 2008 10:05:09 -0400 Received: from web32602.mail.mud.yahoo.com ([68.142.207.229]:40596 "HELO web32602.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751099AbYEHOFI (ORCPT ); Thu, 8 May 2008 10:05:08 -0400 X-YMail-OSG: KhAR.LAVM1m.lV2Z_o3dUQlPtBt53pOdyhy.Ib3hDdTm7r_VabpjPjG5gwJ13tp5yA-- X-Mailer: YahooMailRC/975.23 YahooMailWebService/0.7.185 Date: Thu, 8 May 2008 07:05:05 -0700 (PDT) From: Martin Knoblauch Subject: Re: 2.6.25.2 - Jiffies/Time jumping back and forth (Regereesion from 2.6.24) To: Gabriel C , Thomas Gleixner Cc: Bart Van Assche , linux-kernel@vger.kernel.org, hmh@hmh.eng.br MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Message-ID: <295530.5900.qm@web32602.mail.mud.yahoo.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- Original Message ---- > From: Gabriel C > To: Thomas Gleixner > Cc: Martin Knoblauch ; Bart Van Assche ; linux-kernel@vger.kernel.org; hmh@hmh.eng.br > Sent: Thursday, May 8, 2008 2:21:57 PM > Subject: Re: 2.6.25.2 - Jiffies/Time jumping back and forth (Regereesion from 2.6.24) > > Thomas Gleixner wrote: > > On Wed, 7 May 2008, Martin Knoblauch wrote: > >>> no this looks different. As soon as the timesource is detected, I see > non-zero > >>> timestamps > >>> in dmesg, but they look smaller and jump in both directions. And I have > never > >>> seen this before > >>> 2.6.25. > >>> > >>> It actually might be a good idea to get the dmesg output from 2.6.24. > >>> > >>> Cheers > >>> Martin > >> interesting - maybe related to clocksources. The HPET seems to be detected > later in 2.6.25: > >> > >> 2.6.24: > >> > >> [ 0.000000] Initializing CPU#0 > >> [ 0.000000] PID hash table entries: 4096 (order: 12, 32768 bytes) > >> -->[ 0.000000] hpet clockevent registered > >> -->[ 0.000000] TSC calibrated against HPET > > > >> 2.6.25.2: > >> > >> [ 0.000000] Initializing CPU#0 > >> [ 0.000000] PID hash table entries: 4096 (order: 12, 32768 bytes) > >> -->[ 0.000000] TSC calibrated against PM_TIMER > > > > That's odd indeed. Is HPET not registered at all in 2.6.25 or does it just > happen late ? > > > > please provide the output of: > > /sys/devices/system/clocksource/clocksource0/available_clocksource > > /sys/devices/system/clocksource/clocksource0/current_clocksource > > I was about to report / ask bout this issue too. > > I see the same output for >=2.6.25 , TSC calibrated against PM_TIMER and not > against HPET anymore. > > > [ 0.000000] TSC calibrated against PM_TIMER > [ 0.000016] time.c: Detected 2499.949 MHz processor. > ... > [ 0.000999] hpet clockevent registered > > So it seems to register to late in >=2.6.25 kernels ? > > cat /sys/devices/system/clocksource/clocksource0/available_clocksource > tsc hpet acpi_pm jiffies > > cat /sys/devices/system/clocksource/clocksource0/current_clocksource > tsc > > on two different systems running 2.6.25.2: ibm x3650(2xDualCore) ------------------------------------- [root@lpsdm60 ~]# cat /sys/devices/system/clocksource/clocksource0/available_clocksource tsc hpet acpi_pm jiffies [root@lpsdm60 ~]# cat /sys/devices/system/clocksource/clocksource0/current_clocksource tsc HP Proliant DL-380G4 (2xSingleCore) ------------------------------------------------------------ [root@lpsdm52 ~]# cat /sys/devices/system/clocksource/clocksource0/available_clocksource tsc hpet acpi_pm jiffies [root@lpsdm52 ~]# cat /sys/devices/system/clocksource/clocksource0/current_clocksource tsc and on the DL380G4 running 2.6.24: --------------------------------------------------------- [root@lpsdm52 ~]# cat /sys/devices/system/clocksource/clocksource0/available_clocksource hpet acpi_pm jiffies tsc [root@lpsdm52 ~]# cat /sys/devices/system/clocksource/clocksource0/current_clocksource hpet Cheers Martin