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On 24/08/2017 00:29, R0b0t1 wrote: |
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> As an example, I am interested in characterizing the power consumption |
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> of rendering a PDF document. I would hopefully only need to run the |
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> renderer once. |
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> |
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> I can use PowerTOP, but it seems to be limited to rough measurements |
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> on the order of tenths of a watt. This measurement can be divided |
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> among the wakeup events in an attempt to calculate software power |
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> consumption but it seems imperfect if I want to monitor a single |
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> process that may be competing relatively equally for resources with |
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> the kernel and other user processes. |
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> |
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> PMBus is a spinoff of SMBus which is a spinoff of I2C which is found |
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> on many motherboards. PMBus is supposed to be the interface which |
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> controls and reports power supply activity. Besides the main kW power |
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> supply, there is usually a power supply near your processor that steps |
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> down 3.3V or 5V to 2.8V, 1.8V, or lower (I've seen as low as 0.8V, but |
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> not on a desktop). I was not aware these had a visible interface. |
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> |
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> Apparently you can talk to these, but my searches can only find code |
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> which seems highly experimental. The other replies seem to be for |
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> embedded Linux systems running on FPGAs and perhaps Cortex-A parts. |
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> |
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> If I were using a microcontroller I could get uA or nA draw per MHz |
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> and I know my operating voltage and operating time. However, desktop |
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> processors are much more complex, and I am not sure if they have been |
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> entirely characterized. The most advanced tool I can find is PowerTOP |
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> and it does not seem very accurate. |
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> |
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> Does anyone have any suggestions? Should I start reading source code |
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> or post on the forums? |
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Both of these sound good |
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> Or perhaps someone has used PowerTOP and found |
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> it to be reasonably accurate? |
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No not this. PowerTOP was designed to find badly-behaving programs like |
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pidgin that woke up and polled it's queue every 1ms or so. It's not for |
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what you want at all, not even close. |
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> |
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> R0b0t1. |
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> |
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-- |
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Alan McKinnon |
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alan.mckinnon@×××××.com |
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