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From: Larry Finger <Larry.Finger@lwfinger.net>
To: LKML <linux-kernel@vger.kernel.org>
Subject: Regression in 4.8 - CPU speed set very low
Date: Fri, 9 Sep 2016 12:39:27 -0500	[thread overview]
Message-ID: <f89dffb9-cc78-9849-9539-74ce89e773cd@lwfinger.net> (raw)

I have found a regression in kernel 4.8-rc2 that causes the speed of my laptop 
with an Intel(R) Core(TM) i7-4600M CPU @ 2.90GHz to suddenly have a maximum cpu 
frequency of ~400 MHz. Unfortunately, I do not know how to trigger this problem, 
thus a bisection is not possible. It usually happens under heavy load, such as a 
kernel build or the RPM build of VirtualBox, but it does not always fail with 
these loads. In my most recent failure, 'hwinfo --cpu' reports cpu MHz of 
396.130 for #3. The bogomips value is 5787.73, and the cpu clock before the 
fault is 3437 MHz. Nothing is logged when this happens.

If I were to get a patch that would show a backtrace when the maximum CPU 
frequency is changed, perhaps it would be possible to track this bug.

Sorry that I can not be more specific.

Larry

             reply	other threads:[~2016-09-09 17:39 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-09 17:39 Larry Finger [this message]
2016-09-14 16:00 ` Regression in 4.8 - CPU speed set very low Larry Finger
2016-09-19  2:54   ` Larry Finger
2016-09-24  2:45     ` Larry Finger
2016-09-26 11:37       ` Rafael J. Wysocki
2016-09-26 16:15         ` Larry Finger
2016-09-26 21:06           ` Rafael J. Wysocki
2016-09-26 21:26             ` Srinivas Pandruvada
2016-09-26 21:30               ` Rafael J. Wysocki
2016-09-26 21:41                 ` Srinivas Pandruvada
2016-09-26 21:46                   ` Rafael J. Wysocki
2016-09-26 21:28             ` Larry Finger
2016-09-26 21:37               ` Rafael J. Wysocki
2016-09-26 21:46                 ` Srinivas Pandruvada
2016-09-26 22:15                   ` Larry Finger
2016-09-26 22:09                 ` Larry Finger
2016-09-26 22:16                   ` Rafael J. Wysocki
2016-09-26 23:53                     ` Larry Finger
2016-09-27  0:21                       ` Rafael J. Wysocki
2016-09-27  0:48                         ` Larry Finger
2016-09-27  1:30                           ` Srinivas Pandruvada
2016-09-27  2:53                             ` Larry Finger
2016-09-27  3:12                           ` Doug Smythies
2016-09-27  8:48                             ` Larry Finger
2016-09-27 11:46                               ` Rafael J. Wysocki
2016-09-29  2:22                                 ` Larry Finger
2016-09-29 12:19                                   ` Rafael J. Wysocki
2016-09-29 15:09                                     ` Larry Finger
2016-09-29 15:56                                     ` Srinivas Pandruvada
2016-09-29 16:24                                       ` Larry Finger
2016-09-29 20:52                                       ` Rafael J. Wysocki
2016-09-30 21:52                                       ` Larry Finger
2016-09-27 14:51               ` Lennart Sorensen
2016-09-29  2:26                 ` Larry Finger
2016-09-29 14:17                   ` Lennart Sorensen

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