2010年5月17日 星期一

Speculative prefetching on ARM processor

ARM: dma-mapping: fix for speculative prefetching
http://kerneltrap.org/mailarchive/git-commits-head/2010/3/1/25335
(Russell's patch regarding speculative prefetching)

Cortex-A9 Technical Reference Manual: 6.5.2. Data prefetching and monitoring
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0388e/CHDIGCEB.html

The Cortex-A9 data cache implements an automatic prefetcher that monitors cache misses done by the processor. This unit can monitor and prefetch two independent data streams. It can be activated in software using a CP15 Auxiliary Control Register bit. See Auxiliary Control Register.

When the software issues a PLD instruction the PLD prefetch unit always takes precedence over requests from the data prefetch mechanism. Prefetched lines in the speculative prefetcher can be dropped before they are allocated. PLD instructions are always executed and never dropped.

PLD, PLDW, and PLI
http://www.keil.com/support/man/docs/armasm/armasm_cjadcfdc.htm

MPlayer在ARM开发板的移植
http://blog.chinaunix.net/u3/105675/showart_2148571.html
(seems on armv4l, not related to speculative prefetching)

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