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Method to monitor the time a core was folded from an operating system environment

IP.com Disclosure Number: IPCOM000223782D
Publication Date: 2012-Nov-29
Document File: 6 page(s) / 200K

Publishing Venue

The IP.com Prior Art Database

Abstract

Method to monitor the time a core was put to sleep from OS environment

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This is the abbreviated version, containing approximately 52% of the total text.

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Method to monitor the time a core was folded from an operating system environment

Virtual processor folding is one of the power saving features available in POWER architecture , where if the virtual processors are idle, their VP is marked as disabled and ceded back to hypervisor and the hypervisor puts the core to sleep . The hypervisor may choose to donate the processor or put the core to sleep based on the processor needs . If donated, the donated time ( in PURR ) is updated by hypervisor, else if put to sleep, the time put to sleep is not accounted to any different bucket , sothe OS accounts that time as idle time. In this disclosure we would look at a method to separate the idle time and the time the processor was put to sleep and include a metric to study the effectiveness of partitions with regards to power saving by processor folding .

In this disclosure we will look at two methods to separate the time the processor was put to deep sleep state and a formula to identify the power saving efficiency of LPAR with respect to processor folding .

We will look at two methods to get the time a cpu was put to sleep by core .


1. Usually, the hypervisor notes the time base value before the core is put to sleep and when the cpu wakes up , the time delta is calculated and accounted equally to all the threads . Since this accounting happens only after cpu isunfolded , there is a sudden spike in purr values noted from OS environment . If the same delta is updated as a new metric in pvpa structure , this value could be used by OS to get the sleep time directly and this will be more accurate .

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2. We could approximate...