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Zero Loads: Canceling Load Requests by Tracking Zero Values

Mafijul Islam (Institutionen för data- och informationsteknik, Datorteknik (Chalmers)) ; Per Stenström (Institutionen för data- och informationsteknik, Datorteknik (Chalmers))
9th MEDEA Workshop on MEmory Performance: DEaling with Applications, Systems and Architecture, MEDEA '08, Held in Conjunction with the PACT 2008 Conference; Toronto, ON; Canada; 26 October 2008 through 26 October 2008 Vol. 310 (2008), p. 16-23.
[Konferensbidrag, refereegranskat]

The considerable gap between processor and DRAM speed and the power losses in the cache hierarchy calls for more efficient approaches. Broadly speaking, cache-hierarchy efficiency can be increased either by improving cache management or by reducing the number of load instructions that reach the cache hierarchy. We introduce the notion of zero loads to approach the latter. This paper explores the potential of tracking locations that contain the value 'zero'. Loads directed to such locations - termed Zero Loads - can be cancelled before they are issued in the cache hierarchy. We find that as many as 21% of the loads are Zero Loads and about one third of them are critical, i.e., ends up on the critical memory path for out-of-order cores. Motivated by this observation, we explore two innovative structures to capture Zero Loads by essentially book-keeping earlier visited blocks/locations that return 'zero'. These schemes are shown to be capable of improving performance and power/energy efficiency considerably.

Denna post skapades 2008-09-23. Senast ändrad 2016-05-04.
CPL Pubid: 74288


Institutioner (Chalmers)

Institutionen för data- och informationsteknik, Datorteknik (Chalmers)


Information Technology

Chalmers infrastruktur

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Zero-Value Caches: Cancelling Loads that Return Zero