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System and Method of compression based on Home Scheduler Resource Affinity Domain.

IP.com Disclosure Number: IPCOM000241699D
Publication Date: 2015-May-22
Document File: 4 page(s) / 61K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a Method of considering the Scheduler Resource Affinity Domain(SRAD) while expanding the effective memory capacity of the system by compressing least recently used un-compressed pages into compressed pages. This article contains mainly the way of spreading its compressed pool & uncompressed pool across all available SRAD, Identify the home SRAD of the page to be compressed and policy for allocating particular compression space for a page. It will increase the efficiency of the Active memory expansion.

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System and Method of compression based on Home Scheduler Resource Affinity Domain.

Active Memory Expansion :

Active Memory Expansion (AME) is a technology for expanding a system's effective memory capacity. AME employs memory compression technology to transparently compress the in-memory data to increase the amount of data that can be placed into memory and thus expand the effective memory capacity of a POWER processor based system.

This technology works as follows:

The entire Memory in the system will be divided into 2 pools :

1. Compressed Pool

2. Uncompressed Pool.

The Compressed Pool size greatly varies based on the workloads and configuration of the system. When an application needs to access data that is compressed, the operating system automatically extracts the data from the compressed pool and moves it to the uncompressed pool, making it available to the application. When there is high memory requirement from Application ( this new demand will be satisfied from uncompressed pool ) the operating system compresses the data and moves it from the uncompressed pool to the compressed pool. This compression and decompression activity is transparent to the application.

Memory pages that goes into the compressed pool are mainly of the following types.


1. Pages which are least recently used.

2. The pages that have 0 or no cpu cycles.

SRAD Scheduler Resource Affinity Domain :

SRAD is a group of resources but in our case CPU/cores and the associated memory that is directly attached to it.

Example : A SRAD might have logical CPUs 4, 5, 6 and 7 (i.e. the logical CPUs of the second physical CPU/core) and 25 GB of memory. With a process that is running in this SRAD, any memory it gets allocated at time X or later on with malloc() with be assigned from the 25 GB of memory pertaining to that SRAD.

If memory in that particular SRAD is not enough to satisfy the demand, AIX operating

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system may forces to allocate memory from the memory which is far.

If the process tries to access memory pages present in remote SRAD suffers poor performance.

Background :

Compression logic works on a System wide scope. Decompression works in process context. If the page to be decompresse...