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* [PATCH 0/2]  Quiet power limit notification
@ 2013-05-15 13:36 Fenghua Yu
  2013-05-16 21:54 ` [RESEND] " Len Brown
  0 siblings, 1 reply; 10+ messages in thread
From: Fenghua Yu @ 2013-05-15 13:36 UTC (permalink / raw)
  To: Rafael Wysocki, Len Brown; +Cc: linux-kernel, x86, linux-pm, Fenghua Yu

From: Fenghua Yu <fenghua.yu@intel.com>

Power Limit Notification (X86_FEATURE_PLN) was added in Sandy Bridge
to give the OS the option of knowing when the package has reached
a configured power threshold.

Linux-2.6.36 enabled this feature:
0199114c31798af5b83841b21759b64171060d9b
(x86, hwmon: Package Level Thermal/Power: power limit)

It enabld the interrupt, and the interrupt hander
added to the MCE log and printed to the console:

printk(KERN_CRIT "CPU%d: %s power limit notification (total events = %lu)
printk(KERN_INFO "CPU%d: %s power limit normal\n"

However, these events are quite routine on some systems under some conditions,
alarming customers and provoking un-necessary customer support calls.

So the MCE log entry was deleted in Linux-3.3:

29e9bf1841e4f9df13b4992a716fece7087dd237
(x86, mce, therm_throt: Don't report power limit and package level thermal throttle events in mcelog)

Here we delete the corresponding kernel console messages,
and then we disable the interrupt by default -- allowing it
to be enabled by cmdline for diagnosis purposes.

https://bugzilla.kernel.org/show_bug.cgi?id=36182

This pair of patches applies cleanly back to Linux-3.3.


^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: [RESEND 2] [PATCH 0/2] Rewrite power limit notification interrupt handling
@ 2013-05-29 18:14 Prarit Bhargava
  0 siblings, 0 replies; 10+ messages in thread
From: Prarit Bhargava @ 2013-05-29 18:14 UTC (permalink / raw)
  To: linux-kernel; +Cc: len.brown

Len,

>The "Power Limit Notification" (X86_FEATURE_PLN) was added in Sandy Bridge
>to give the OS the option of knowing when the package has reached
>a configured power threshold.

>printk(KERN_CRIT "CPU%d: %s power limit notification (total events = %lu)
>printk(KERN_INFO "CPU%d: %s power limit normal\n"

I'm seeing this on a widening number of systems, mostly newer Intel systems.

>However, these events are quite routine on some systems under some conditions,
>alarming customers and provoking un-necessary customer support calls.

The idea that these are "routine" just doesn't make sense to me.  Either this
warning is firing for a valid reason or it isn't.  If it isn't then the question
remains -- why is it firing?  Is it because of buggy FW or is something
actually wrong with the hardware?

P.

^ permalink raw reply	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2013-06-25 18:53 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-05-15 13:36 [PATCH 0/2] Quiet power limit notification Fenghua Yu
2013-05-16 21:54 ` [RESEND] " Len Brown
2013-05-21 16:53   ` [RESEND 2] [PATCH 0/2] Rewrite power limit notification interrupt handling Len Brown
2013-05-21 19:35   ` [PATCH 1/2] x86 thermal: Delete power-limit-notification console messages Len Brown
2013-05-21 19:35     ` [PATCH 2/2] x86 thermal: Disable power limit notification interrupt by default Len Brown
2013-05-22  4:54     ` [PATCH 1/2] x86 thermal: Delete power-limit-notification console messages R, Durgadoss
2013-05-22 23:31       ` Yu, Fenghua
2013-05-28  2:17     ` Zhang Rui
2013-06-25 18:53       ` Yu, Fenghua
  -- strict thread matches above, loose matches on Subject: below --
2013-05-29 18:14 [RESEND 2] [PATCH 0/2] Rewrite power limit notification interrupt handling Prarit Bhargava

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