DOCUMENT ID: 1327-02

SYNOPSIS:    A description of How Solaris handles Physical Address Cache

OS RELEASE:  2.4

PRODUCT:     Solaris

KEYWORDS:    physical cache address buffer mmu memory
 
 
DESCRIPTION:

How physical Address Cache is handled by Solaris 2.4?
 

SOLUTION:

                        Physical Address Cache

A physical cache is a high-speed buffer between the MMU and physical
memory.

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 Stack

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 Hole                                          Physical
                                               address
 -------    CPU ---------> MMU --------> Cache ---------> Physical memory
                Virtual
 Data           address

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 Text

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A physically addressed cache is one that uses the physical address of a
piece of data to determine where in cache it should be located.  A
disadvantage to this type of cache is the fact that for every address
accessed by the CPU, an MMU translation must be completed regardless of
whether the data is in cache.  However, a physical address cache greatly
reduces potential cache aliasing problems. 

 
DATE APPROVED: 05/08/95