Re: [Powertop] PowerTOP 2.0 bugs

[Chris Ferron <chris.e.ferron at linux.intel.com>]

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On 05/14/2012 04:11 PM, Marti Raudsepp wrote:
> On Tue, May 15, 2012 at 1:05 AM, Chris Ferron
> <chris.e.ferron(a)linux.intel.com>  wrote:
>> Can you please tell me what system, processors and distro (and version) you
>> are running?
>> Also are you running in a VM by chance?
> No VM, physical hardware. Arch Linux (testing repos enabled), kernel
> 3.3.5, x86_64.
>
> Bug #1 occurs on my desktop (AMD Phenom II X4 965) as well as laptop
> (Intel Core i5-560M)
OK, lets start with bug 1. It seem there is a definite issues with 
non-intel processors.
Problem is I am having a hard time getting my hands on a non-intel based 
system.
Second part of my thoughts is you are seeing a issues wiht you AMD, but 
you Core i5
may look similar but actually i suspect is not incorrect. From you 
example for bug 1, I am assumeing by what I am seeing that you took 
those numbers from your AMD system.
The reason this is important to define, is there is different code paths 
for Intel and non-intel processors, so getting comparable data between 
them is important. In other words there are three general areas where is 
issue could be happening, and if you are actually seeing the same issue 
on both processors then it points to the only 1 point that is shard in 
this area.

In regards to your Intel system. You could be seeing more the 100% of 
cpus. This is the measurement of the cpus not the package. I don't have 
the full data sheet for your CPU, but you may see up to 400% as your 
system has 2cores with two threads each. 400% of the cpu = 100% of the 
package.
  You may also see such number while looking at Frequency and C0 active. 
For instance 100% would indicate that you are pegged at the Stamped rate 
(which is not the max for an Intel processor). over 100% indicates the 
the freq governor is running the processor higher then the stamped rate. 
So for instance the stamped rate on my i7 is 3.4GHz, and in turbo mode I 
can see the rates at 3.5GHz to 3.8GHz at times. So at ~3.5GHz I would 
see 102.5% as C0 active as it's about ~2.2 to 2.5% per bin of 100Hz.

At this point I think for Bug1, this is an issue with the "last_stamp" 
not getting zeroed out, and the effective freq measurements. It could be 
something as simple as below, but like I said I haven't gotten a AMD 
system to work with.

Could you reproduce Bug 1 and send me the data for each Processor, and 
if you feel so inclined maybe play with the changes below on you AMD 
system.

Thanks
Chris



diff --git a/src/cpu/cpu_linux.cpp b/src/cpu/cpu_linux.cpp
index ab37d57..8aa9772 100644
--- a/src/cpu/cpu_linux.cpp
+++ b/src/cpu/cpu_linux.cpp
@@ -59,6 +59,8 @@ void cpu_linux::measurement_start(void)

         abstract_cpu::measurement_start();

+       last_stamp = 0;
+
         len = sprintf(filename, 
"/sys/devices/system/cpu/cpu%i/cpuidle", number);

         dir = opendir(filename);
@@ -365,6 +367,7 @@ void cpu_linux::change_effective_frequency(uint64_t 
time, uint64_t frequency)

         effective_frequency = frequency;
         last_stamp = time;
+       abstract_cpu::change_effective_frequency(time, frequency);
  }