From: Jiri Slaby <jslaby@suse.cz>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
clemens@ladisch.de, venki@google.com,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: HPET causes tasks to freeze (still in 2.6.36-rc6)
Date: Tue, 12 Oct 2010 00:02:08 +0200 [thread overview]
Message-ID: <4CB38960.5070306@suse.cz> (raw)
In-Reply-To: <alpine.LFD.2.00.1010041747550.14550@localhost6.localdomain6>
On 10/04/2010 06:31 PM, Thomas Gleixner wrote:
> On Mon, 4 Oct 2010, Jiri Slaby wrote:
>> HPET as a clocksource has still issues in the latest kernels (confirmed
>> in 2.6.36-rc6) at least on x86_64. Unless clocksource=jiffies,
>> clocksource=tsc or nolapic_timer is used, the system is unusable. Tasks
>> are not woken unless mouse is moved, key is pressed (or other hard irq
>> triggered). 2.6.32 seems to be the last working.
>
> The problem is not clocksource related, it's NOHZ related.
>
> clocksource=jiffies, clocksource=tsc are disabling NOHZ simply because
> we can not do NOHZ neither with jiffies nor with a TSC which stops in
> deeper C-states.
>
> nolapic_timer installs a dummy lapic timer so the lapic is not used,
> but HPET is used instead and NOHZ is disabled as well.
>
> So the real problem is that the hpet broadcast interrupts which are
> used to work around the lapic timer stops in C3 problem are not coming
> through for whatever reason.
>
> So the question is what changed in the ACPI/idle NOHZ code which might
> expose this problem.
>
> Can we get dmesg, output of proc/timer_list and output of
> /proc/acpi/processor/CPU0/power for a .32 and a non working kernel
> please ?
Sure:
http://labs.suse.cz/jslaby/bug-579932/
thanks,
--
js
suse labs
next prev parent reply other threads:[~2010-10-11 22:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-04 15:36 HPET causes tasks to freeze (still in 2.6.36-rc6) Jiri Slaby
2010-10-04 15:55 ` Paul Rolland
2010-10-04 16:31 ` Thomas Gleixner
2010-10-11 22:02 ` Jiri Slaby [this message]
2010-10-20 9:38 ` Jiri Slaby
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