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From: Greg KH <gregkh@linuxfoundation.org>
To: dirk.brandewie@gmail.com
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
	rafael.j.wysocki@intel.com, gf435@gmx.net, bp@alien8.de,
	Dirk Brandewie <dirk.j.brandewie@intel.com>
Subject: Re: [PATCH] intel_pstate: Change busy calculation to use fixed point math.
Date: Fri, 28 Feb 2014 14:47:41 -0800	[thread overview]
Message-ID: <20140228224741.GA31233@kroah.com> (raw)
In-Reply-To: <1393353337-19778-1-git-send-email-dirk.j.brandewie@intel.com>

On Tue, Feb 25, 2014 at 10:35:37AM -0800, dirk.brandewie@gmail.com wrote:
> From: Dirk Brandewie <dirk.j.brandewie@intel.com>
> 
> Commit fcb6a15c2e Take core C0 time into account for core busy calculation.
> 
> Introduced a regression on some processor SKUs supported by
> intel_pstate. This was caused by the truncation caused by using
> integer math to calculate core busy and C0 percentages.
> 
> On a i7-4770K processor operating at 800Mhz going to 100% utilization
> the percent busy of the CPU using integer math is 22% it actually is
> 22.85%.  This value scaled to the current frequency returned 97 which
> the PID interpreted as no error and did not adjust the P state.
> 
> Tested on i7-4770K, i7-2600, i5-3230M
> 
> References:
>    https://lkml.org/lkml/2014/2/19/626
>    https://bugzilla.kernel.org/show_bug.cgi?id=70941
> 
> Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>

Thanks, this fixed the issue for me:

Tested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

      parent reply	other threads:[~2014-02-28 22:46 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-19 22:47 Commit fcb6a15c2e7e (intel_pstate: Take core C0 time into account for core busy calculation) sucks rocks Greg KH
2014-02-20  0:03 ` Dirk Brandewie
2014-02-20  0:35   ` Greg KH
2014-02-20  0:51     ` Greg KH
2014-02-20 14:56       ` Dirk Brandewie
2014-02-20 18:10         ` Greg KH
2014-02-24 22:37           ` Greg KH
2014-02-24 23:03             ` Dirk Brandewie
2014-02-25 18:35 ` [PATCH] intel_pstate: Change busy calculation to use fixed point math dirk.brandewie
2014-02-26  0:39   ` Rafael J. Wysocki
2014-02-26 14:57     ` Otto Meier
2014-02-28 22:47   ` Greg KH [this message]

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