beautypg.com

M.1.2 level-1 data cache (l1d cache), M.1.3 level-2 unified cache (l2 cache) – FUJITSU Implementation Supplement Fujitsu SPARC64 V User Manual

Page 138

background image

Release 1.0, 1 July 2002

F. Chapter M

Cache Organization

127

M.1.2

Level-1 Data Cache (L1D Cache)

The level-1 data cache is a writeback cache. Its characteristics are shown in

TABLE M-2

.

Although L1D cache is VIPT,

TTE.CV

is ineffective since SPARC64 V has unaliasing

features in hardware.

Data accesses bypass the L1D cache when they are noncacheable accesses.
Noncacheable accesses occur under one of three conditions:

The ASI used for the access is either

ASI_PHYS_BYPASS_EC_WITH_E_BIT

(15

16

)

or

ASI_PHYS_BYPASS_EC_WITH_E_BIT_LITTLE

(1D

16

).

DCUCR.DM

= 0

TLB.CP

= 0

Unlike the L1I cache, the L1D cache does not use

MCNTL.NC_CACHE

.

M.1.3

Level-2 Unified Cache (L2 Cache)

The level-2 unified cache is a writeback cache. Its characteristics are shown in

TABLE M-3

.

The L2 cache is bypassed when the access is noncacheable.

MCNTL.NC_CACHE

is not

used on the L2 cache.

TABLE M-2

L1D Cache Characteristics

Feature

Value

Size

128 Kbytes

Associativity

2-way

Line Size

64-byte

Indexing

Virtually indexed, physically tagged (VIPT)

Tag Protection

Parity and duplicate

Data Protection

ECC

TABLE M-3

L2 Cache Characteristics

Feature

Value

Size

2 Mbytes

Associativity

2- or

4-way, in

ASI_L2_CTRL

(6A

16

)

Line Size

64-byte

Indexing

Physically indexed, physically tagged (PIPT)

Tag Protection

ECC

Data Protection

ECC