From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dragan Noveski Subject: Re: High resolution timers on ACPI-less kernel Date: Tue, 09 Oct 2007 17:59:43 +0200 Message-ID: <470BA56F.9090509@gmx.net> References: <470B44A1.7080007@free.fr> <1191921343.13628.0.camel@godzilla.tecnorama.it> <470B49BD.4070506@free.fr> <470B5971.40601@free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: linux-rt-users@vger.kernel.org Return-path: Received: from mail.gmx.net ([213.165.64.20]:57435 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754649AbXJIQA1 (ORCPT ); Tue, 9 Oct 2007 12:00:27 -0400 In-Reply-To: <470B5971.40601@free.fr> Sender: linux-rt-users-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org John Sigler wrote: > Thomas Gleixner wrote: >> On Tue, 9 Oct 2007, John Sigler wrote: >>> Alessio Igor Bogani wrote: >>>> On Tue, 2007-10-09 at 11:06 +0200, John Sigler wrote: >>>> >>>>> I enabled high resolution timer support and disabled ACPI support. >>>> >>>> http://www.mail-archive.com/linux-rt-users@vger.kernel.org/msg00375.html >>>> >>> >>> There are other clock sources on my system. >>> The timestamp counter is reliable (as far as I can tell). >> >> See previous mail. >> >>> The LAPIC timer is reliable. >> >> LAPIC timer is a clock event device, not a clock source. It can be >> used to program the next event, but not to read the time. >> >>> (I've just disabled the PM timer.) >> >> Yup, which in turn disables highres. > > OK. I have two more questions. > > Can the kernel verify the correctness of the TSC with the PIT? > > When I enable the ACPI PM timer, the kernel tells me: > > * The chipset may have PM-Timer Bug. Due to workarounds for a bug, > * this clock source is slow. If you are sure your timer does not have > * this bug, please use "acpi_pm_good" to disable the workaround > > How can I tell whether my PM timer has this bug or not? > (Specific revision? Test app?) > > Regards. > hallo, i am using the 2.6.22.1-rt9 kernel too, and it runs pretty good for me, but following this thread i got very unsure, if the hrtimer is being used here. please, i would really appreciate if someone of you could make a 'diagnosis' of the issue. murija2:/home/nowhiskey# cat /sys/devices/system/clocksource/clocksource0/available_clocksource tsc hpet acpi_pm pit jiffies murija2:/home/nowhiskey# cat /sys/devices/system/clocksource/clocksource0/ available_clocksource current_clocksource murija2:/home/nowhiskey# cat /sys/devices/system/clocksource/clocksource0/current_clocksource tsc murija2:/home/nowhiskey# cat /proc/timer_list Timer List Version: v0.3 HRTIMER_MAX_CLOCK_BASES: 2 now at 279500939467 nsecs cpu: 0 clock 0: .index: 0 .resolution: 1 nsecs .get_time: ktime_get_real .offset: 1191944919927389648 nsecs active timers: clock 1: .index: 1 .resolution: 1 nsecs .get_time: ktime_get .offset: 0 nsecs active timers: #0: , tick_sched_timer, S:01 # expires at 279501000000 nsecs [in 60533 nsecs] #1: , it_real_fn, S:01 # expires at 279519610937 nsecs [in 18671470 nsecs] #2: , hrtimer_wakeup, S:01 # expires at 279911555013 nsecs [in 410615546 nsecs] #3: , hrtimer_wakeup, S:01 # expires at 285349267955 nsecs [in 5848328488 nsecs] #4: , it_real_fn, S:01 # expires at 292823897860 nsecs [in 13322958393 nsecs] #5: , hrtimer_wakeup, S:01 # expires at 307102248124 nsecs [in 27601308657 nsecs] #6: , hrtimer_wakeup, S:01 # expires at 307167956204 nsecs [in 27667016737 nsecs] .expires_next : 279501000000 nsecs .hres_active : 1 .nr_events : 43411 .nohz_mode : 2 .idle_tick : 279482000000 nsecs .tick_stopped : 0 .idle_jiffies : 4294946777 .idle_calls : 33246 .idle_sleeps : 27192 .idle_entrytime : 279481048513 nsecs .idle_sleeptime : 248235489890 nsecs .last_jiffies : 4294946777 .next_jiffies : 4294946817 .idle_expires : 279521000000 nsecs jiffies: 4294946796 Tick Device: mode: 1 Clock Event Device: pit max_delta_ns: 27461866 min_delta_ns: 12571 mult: 5124677 shift: 32 mode: 3 next_event: 9223372036854775807 nsecs set_next_event: pit_next_event set_mode: init_pit_timer event_handler: tick_handle_oneshot_broadcast tick_broadcast_mask: 00000000 tick_broadcast_oneshot_mask: 00000000 Tick Device: mode: 1 Clock Event Device: hpet max_delta_ns: 2147483647 min_delta_ns: 3352 mult: 61496110 shift: 32 mode: 3 next_event: 279502000000 nsecs set_next_event: hpet_legacy_next_event set_mode: hpet_legacy_set_mode event_handler: hrtimer_interrupt