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Physical separation of known memory hot spots for smoother thermal distribution

IP.com Disclosure Number: IPCOM000177354D
Original Publication Date: 2008-Dec-09
Included in the Prior Art Database: 2008-Dec-09
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Abstract

This invention uses a modified effective-to-physical address mapping to migrate data/instructions to cooler regions of the same memory region when hot spots are detected during run time.

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Physical separation of known memory hot spots for smoother thermal distribution

Historically, the term "hot spot" refers to a region of memory with high access statistics. More recently, this term now refers to a region of physical memory with a higher temperature gradient due to high usage. As processors become faster, the pressure increases for the memory subsystems to serve up application data or instructions. On virtual machines, the physical memory layout is somewhat hidden by the address translation schemes. However, it is just such an address translation scheme that can be used to effectively reduce concentrated thermal stresses on the memory subsystem, reducing the occurrences of hot spots.

This invention uses a modified effective-to-physical address mapping to migrate data/instructions to cooler regions of the same memory region when hot spots are detected during run time.

A typical effective-to-physical address mapping takes a physical address within a range that is allocated to, say a virtual machine's LPAR (Logical PARtition), for example, and maps it to an effective address . A certain range of physical memory is allocated to an LPAR when it is created. In the IBM™ implementation this memory is striped across physical memory domain regions, like across MCM (Multiple Chip Module) regions when the cores allocated to the LPAR cross MCM boundaries. It will be impossible to know at allocation time where the hot spots will be located. Therefore, this invention uses a tabular method during run time to track the memory accesses to provid...