Circuit and method for detecting bank conflicts in accessing adjacent ...

US006393512B1

(12) United States Patent

(10) Patent N0.:

Chen et al.

(45) Date of Patent:

(54) CIRCUIT AND METHOD FOR DETECTING BANK CONFLICTS IN ACCESSING ADJACENT BANKS (75) I A d Y J Ch S 1 nventors:

n rea

.

.

en,

Notice:

unnyva e;

pps. 1—2.

LOI‘dSOII L- Yue, Foster City, both 0f

“Direct RambusTM Memory for Desktop PC Systems”,

CA (Us)

Rambus, Inc., ©May 1998, pps. 1—4. Crisp, “Applications for Rambus® Interface Technology”, Rambus, Inc” ©Feb_ 1998, PPS 1_6_

Subject to any disclaimer, the term of this patent is extended or adjusted under 35

* Cited by examiner Primary EX?min€r—MattheW M. Kim

U_S,C, 154(b) by 0 days,

Assistant Examiner—Christian P. Chace (74) Attorney, Agent, or Firm—Vedder, Price, Kaufman &

(21) Appl. N0.: 09/407,224

Kammholl

(22) Filed:

( )

(51)

52 (

56 (

)

57

Sep. 27, 1999

ABSTRACT

Int. c1.7 .............................................. .. G06F 12/00

A bank Con?lct .detecpr Compares at least a Porno“ of a

U S C]

current address signal (1.e. an address signal generated by a

)

(58)

May 21, 2002

Crisp, “Direct Rambus Technology: The NeW Main Memory Standard”, IEEE Micro, Nov/Dec. 1997, pps. 18—28. “Direct RAC (Rambus® ASIC Cell)”, Rambus Advance Information, Direct RAC Product Summary, ©May 1998,

(73) Assignee: ATI International SRL (BB) (*)

US 6,393,512 B1

I. .

711 5 . ......................................................... ..

/

Fleld 0f Search ............................... .. 711/103, 210, 711/5> 158’ 167 R f Ct d e erences l e

U_S_ PATENT DOCUMENTS

request Currently issued to main memory) With a Corre_

sponding portion of a tobedssued memory address Signal, to determine if a bank con?ict exists. Speci?cally, in one embodiment, the bank con?ict detector includes a number of exclusive OR gates that receive as inputs the tWo addresses to be compared, and generate an output (also called “XOR

result”) that is compared With predetermined patterns to 5,249,280 A :

9/1993 Nfish et al' """"""""" " 711/5

determine if a bank con?ict exists. For example, if the bank

5’323’489 A

6/1994 Bud """" "

711/167

con?ict detector ?nds that the XOR result is 0 (Zero) then the

7/1995

Stamm .... ..

711/156

Lin et a1. ........ ..

711/158

5,432,918 A

5 440 713 A ,

,

*

*

8

/1995

.

.

tWo addresses access the same bank. The bank con?ict _

5,522,059 A * 5/1996 Marushima et aL _

711/149

detector also the XORl‘?SllliWlih patterns that are formed by

5,692,209 A 4 11/1997 Meaney et a1_ 5,740,402 A * 4/1998 Bran et a1_

710/244 711 /157

a number of consecutive 1s 1n the least sigm?cant bits and a number of consecutive Us in the most signi?cant bits. If no

* * *

5/1998 Tran ............... .. 711/125 7/1998 Lieberman et al---- -- 711/5 8/1998 Levitan ~~~~~~~~~~~~~~~~~~~~ ~~ 714/800

match, then the bank con?ict detector determines that no bank con?ict exists. OtherWise, the bank con?ict detector compares at least one of the addresses (both addresses in one

6:029:25 A :

2/2000 McGeheartY et al' ~~~~~~~~ " 711/5

implementation) With one or more predetermined patterns

6935376 A

3/2000 James """""""" "

(e.g. tWo patterns in one implementation), and in case of a

5,752,259 A 5,781,918 A 5,796,758 A

6,125,422 A

*

6,192,487 B1 *

711/145

9/2000 May ........ .. 2/2001

711/5

Douceur ...................... .. 714/8

thdt m C

.

tht

e ermmes

b

a a

k an

?. t

.t

Con 16 6X15 5’ an

d

th 0

. “W156

determines that no bank con?ict exists. These patterns also OTHER PUBLICATIONS

“Direct RDRAMTM 64/72—Mbit (256Kx16/18x16d)”, Ram bus Advance Information, 64M/72M Direct RDRAM Data Sheet, last modi?ed on Mar. 12, 1998; 48 pps. a[n:0]

[11010]

C [n.0] .

I I

I

have Us in the least signi?cant positions and 1s in the most signi?cant positions or vice versa, depending on the imple mentation.

10 Claims, 26 Drawing Sheets

SAME BANK DETECTION UNIT

335

sAME

3

BANK

311 LJ [.1

CONFLICT LJ

2 L858

NH

+1» 326A

1» 327.4 3/‘ 328A ZLSBs 3 L588

340

325A

_

ADJACENCY CiRCUlT

n+1

$329,

+3» 3268 1» 327B 3» 3235

r 3255

ADJACENCY ClRCU/T

32512

SL553

DEPENDENCY DETECTlON UNIT

3291b ‘

W i LSBs

’

3291 w

ADJACENT 3

E

Cg?g?-CT

w 325]

n+1

W329},

n+1LSBS +3» 3261’ 1» .7271J 3’ 3231’

n+1 LSBS

ADJACENCY ClRCUIT

ADJACENT BANK $3251’ DETECTlON WT E

BANK.

CONFLICT

ADJACENCY CIRCUIT

1,1231

ILSBS

0R

326'

N327]

3 41 3

2

DEPENDENT SAME IADJACENT FLAG BANK DETECTOR

H1

M

U.S. Patent

May 21, 2002

Sheet 1 0f 26

US 6,393,512 B1

10

8

MAIN I

MEMORY

-PRIOR ART

FIGJA

U.S. Patent

May 21, 2002

Sheet 2 0f 26

US 6,393,512 B1

22052 WRITE BUFFER

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U.S. Patent

May 21, 2002

Sheet 4 0f 26

US 6,393,512 B1

213A

213.]

213N

8

8

8

I

223M

223A

223J

224 241A~

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BANKvCONFLICTv DETEQia22?

READ WRITE OPTIMIZER

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227 CURRENT CONTROL '

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ARBITER

(OPTIONAL)

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203w MEMORY

FIG.2B

REFRESH REQUESTOR

(OPTIONAL)

U.S. Patent

May 21, 2002

261 w

262 "'

Sheet 5 0f 26

US 6,393,512 B1

@

FIG.2C

COMPUTE ADDRESS OF LOW ADJACENT BANK

SAME IADJACENT

A

2221

BANK DETECTOR

COMPUTE ADDRESS OF HIGH ADJACENT BANK

A; 260 263

268

DDES

8

'PEND ADDR HAVE

BANK ADDR SAME AS

CURRENT BANK

264 DOES BANK AT PEND ADDR HAVE DEPENDENCY

FLAS) SET

DOES

PEND ADDR HAVE BANK ADDR SAME AS

LOW ADJACENT BANK?

266 DOES PEND ADDR HAVE BANK ADDR SAME AS HIGH ADJACENT BANK?

2677\,

BANK CONFL|CT=

TALSE

_

BANKQFQLNELICT -

A A

U.S. Patent

May 21, 2002

Sheet 6 6f 26

mm.

mmm

mmm mm

Eda “ u W? E _ _

m n

_ _

New EN

5.02 @Z H

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NP CH J :25 _

US 6,393,512 B1

I1“iQal_

_:m

; * nwHmx-wwm BANK_CONFL|CT= TRUE _>

[C0_U_NT7-_1:0] + 324 *v

BANK_CONFL|CT = FALSE

FIG.3C

U.S. Patent

m

May 21, 2002

Sheet 14 0f 26

FIG.3D

US 6,393,512 B1

BANK CONFLICT _@ FLAG = TRUE

J

341

IS

3423

C[5:0JDEQUAL 6 000001 TO

IS TO a[1:0] EQUAL

7

2'b01

NO 342

BANK CONFLICT FLAG= FALSE

BANK CONFLICT |S

YES

340

FLAG = TRUE

CIBOJDEQLIALTO 0 000011 ? NO

343

IS

CFQJDESOLTAFTO 7

YES

BANK CONFLICT FLAG = FALSE

BANK CONFLICT

FLAG I TRUE

W 3443 Is NO 01301 EQUAL T0 YES

N0

BANK CONFLICT

BANK CONFLICT

FLAG = FALSE

FLAG = TRUE

EXIT

345

345A

345B

IS

IS

C[5:0lDEQUAL 6 0171111 TO

@1412 EQUAL T0

YES

|

NO

BANK CONFLICT FLAG=FALSE

'b01111

b[4:0g‘001111 EQUAL TO

?

?

YES BANK C_ONFLICT

C520 EQUAL TO

[ 610111111 ? NO

IS

NO

346A YES

IS aIBOIDEOLIALTO 6011111 YES BANK CONFLICT

YES

3463

BANK CONFLICT FLAG = FALSE

Is 015:0] EQUAL T0 000171111 YES

NO

NO

BANK CONFLICT _ FLAG — FALSE

@W FLAG=TRUE

U.S. Patent

May 21, 2002

Sheet 16 0f 26

%

US 6,393,512 B1

BANK CONFLICT T_,@ FLAG = TRUE

1 360

3628 IS

b[1:0] EQUAL TO 2'b10

NO T

YES

BANK CONFLICT

FLAC = TRUE

BANK CONFLICT

FLAG= FALSE

W 3633 IS

b[2:0] EQUAL TO 3'b100 YES BANK CONFLICT

FLAG = FALSE

364A '8

CIBOIDEQIIAL TO

YES

364B '5

am? EQUAL TO

6 0%1111

NO

‘b12000

'8

b[3:0] EQUAL TO

NO

4'b17000

YES

YES

BANK CONFLICT

365

BANK CONFLICT

BANK CONFLICT

FLAG= FALSE

FLAG = TRUE

W

YES BANK CONFLICT

YES

FLAC -TRUE

W 3663 IS

365A IS

C[5IOJDEQUAL 6 0171111 TO YES NO

366

IS [ 6'LT111111

05:0 EQUAL TO ?

366A

NO

YES

NO BANK CONFLICT

YES

FLAG = FALSE

BANK C_ONFL|CT

BANK CONFLICT FLAG= FALSE

D[5IO1DEQUAL 6 1%0000 TO YES

NO

BANK CONFLICT _ FLAG - FALSE

U.S. Patent

May 21, 2002

Sheet 17 0f 26

US 6,393,512 B1

$.65 2am.

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