linux-kernel - Re: [patch 0/4] Only use HPET MSI timers on systems with deep C-state support

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Message-ID: <4B50E3C4.2050305@compro.net>
Date:	Fri, 15 Jan 2010 16:53:08 -0500
From:	Mark Hounschell <markh@...pro.net>
To:	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
CC:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Len Brown <lenb@...nel.org>, linux-kernel@...r.kernel.org,
	"Rafael J. Wysocki" <rjw@...k.pl>, Alain Knaff <alain@...ff.lu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Li, Shaohua" <shaohua.li@...el.com>
Subject: Re: [patch 0/4] Only use HPET MSI timers on systems with deep C-state
 support

On 01/14/2010 08:39 PM, Venkatesh Pallipadi wrote:
> There is a functionality issue reported on some AMD platforms
> http://lkml.indiana.edu/hypermail/linux/kernel/0912.2/01118.html
> wherein, fdformat fails when HPET MSI based percpu timer is used.
> 
> We do not have the real root-cause for that problem. But, that
> report exposed an issue with our current usage HPET MSI timers.
> We use HPET MSI timers even on platforms that do not have
> support for C2/C3 states. On those systems we should rather be
> using LAPIC timers.
> 
> So, this series of patches does just that.
> * Use LAPIC timer when there is always running APIC timer
> * Use LAPIC timer on platforms that do not have support for deep C states
> * Only use HPET MSI timers as percpu timers on systems that have LAPICs
>   that stop in deep C-states _and_ system supports deep C-states
> 
> The change turned out to be more than what I expected, due to
> the current static nature of clockevent rating and unrelated
> issues in acpi processor driver resume path. I also ended up
> touching different subsystems to handle this.
> 
> If the patchset resolves the issue for Mark and if it looks sane
> can one of the maintainers queue it up for .34
> 
> Reported-by: Mark Hounschell <markh@...pro.net>
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
> 

It does resolve my problem

Mark
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