Ex parte SINDHU et al.

Board of Patent Appeals and Interferences

Jun 26, 1998

08188660 (B.P.A.I. Jun. 26, 1998)

Application for patent filed January 27, 1994. 1
According to appellants, this application is a continuation of
Application 07/620,508, filed November 30, 1990, now
abandoned.
1
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today (1)
was not written for publication in a law journal and (2) is
not binding precedent of the Board.
Paper No. 19
UNITED STATES PATENT AND TRADEMARK OFFICE
__________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________
Ex parte PRADEEP S. SINDHU, JEAN-MARC FRAILONG
and JEAN A. GASTINEL
__________
Appeal No. 95-4096
Application No. 08/188,6601
__________
ON BRIEF
__________
Before HAIRSTON, KRASS and FLEMING, Administrative Patent
Judges.
KRASS, Administrative Patent Judge.
DECISION ON APPEAL
Appeal No. 95-4096
Application No. 08/188,660
2
This is a decision on appeal from the final rejection of
claims 2 through 4, the only claims pending in the
application.
The invention is directed to a packet switched bus for
carrying out memory transactions in a shared memory
multiprocessor. The packet switched bus handles multiple
memory transactions (e.g., read/write) in a time overlapping
manner, with each “request” followed at some later time by a
“reply.” These request/reply pairs are logically
disassociated, unlike in circuit switched bus systems which
involve master/slave relationships between the transaction
requester and the responders. In those systems, the master
maintains control of the bus from the time control is granted
until it receives a reply to its request.
The instant invention uses cache memory to enable each of
the processors and the I/O devices to cache addresses locally
that the devices are likely to be writing data to and/or
reading data from. Since this may mean that there could be
multiple copies of a given address at various sites within the
memory system, there must be some provision for avoiding the
potential problems of inconsistent data being employed. While
Appeal No. 95-4096
Application No. 08/188,660
3
the problem has been said to have been solved in circuit
switched bus systems by write back and invalidate data
consistency techniques, the instant invention is said to solve
the problem in packet switched bus systems by the use of
synchronous buses (shown as buses 15a-15i in Figure 1). By a
more efficient use of the available bus bandwidth, the buses
permit transactions to be performed using packets of differing
length, packet lengths being determined by logical
requirements of the transactions rather than by the timing
requirements of the bus.
Independent claim 2 is reproduced as follows:
2. In a shared memory multiprocessor having a main
memory, a plurality of processors, I/O devices, and respective
cache memories coupled to said processors and to said I/O
devices; the improvement comprising
a packet switched bus coupled to said main memory and to
said cache memories for transferring commands, memory
addresses, and data therebetween in compliance with selected
ones of a predefined set of memory transactions, including
transactions that cause multiple copies of at least some of
said data to be updated at different times under the control
of different ones of said processors;
each of said transactions being composed of a request
packet followed at an indeterminate later time by a reply
packet, thereby enabling the request and reply packets for
multiple transactions to be time interleaved on said bus;
Appeal No. 95-4096
Application No. 08/188,660
4
said transactions being selected to enforce a consistency
protocol that ensures that all of said processors and all of
said I/O devices have access to consistent values for all data
stored in said cache memories, including all data represented
by said multiple copies.
The examiner relies on the following references:
Baxter et al. (Baxter) 4,535,448 Aug. 13,
1985
Dashiell et al. (Dashiell) 4,843,542 Jun. 27,
1989
Claims 2 through 4 stand rejected under 35 U.S.C. 112,
second paragraph, as being indefinite. Claims 2 through 4
stand further rejected under 35 U.S.C. 103 as unpatentable
over Dashiell in view of Baxter.
Rather than reiterate the arguments of appellants and the
examiner, reference is made to the briefs and answer for the
respective details thereof.
OPINION
Turning first to the rejection of claims 2 through 4
under 35 U.S.C. 112, second paragraph, we will not sustain
this rejection.
Appeal No. 95-4096
Application No. 08/188,660
5
The examiner rejects the claims as being “functional” and
not being “supported by recitation of sufficient structure to
warrant the presence of the functional language” [answer- page
3]. We disagree.
We note that the examiner cites MPEP 706.03(c) as
authority for a rejection based on claims being “functional.”
Reference to this section of the MPEP, however, indicates that
the section refers to rejections under the first paragraph of
35 U.S.C. 112 which would include lack of best mode, written
description and enablement problems. There is nothing therein
giving the examiner authority to reject a claim as being
“functional.”
In any event, our review of instant claims 2 through 4
reveals nothing therein which would be considered indefinite
within the meaning of 35 U.S.C. 112, second paragraph. The
claims recite the general structure which comprises a shared
memory multiprocessor system, such as a main memory, a
plurality of processors, I/O devices and cache memories. The
claims further recite a packet switched bus coupled to the
main memory and to the cache memories for transferring
commands, memory addresses and data between the memories in
Appeal No. 95-4096
Application No. 08/188,660
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accordance with selected ones of a predefined set of memory
transactions. Some of these transactions may cause multiple
copies of at least some of the data to be updated at different
times. The remainder of the claims contain recitations as to
what comprises the transactions and how the transactions are
selected as well as more details as to the request and reply
packets.
It may be that the claim language is rather broad but the
examiner should not confuse breadth with indefiniteness. See
In re Miller, 441 F.2d 689, 693, 169 USPQ 597, 600 (CCPA
1971).
We now turn to the rejection based on prior art. We will
not sustain this rejection as it is our view that the examiner
has not established a prima facie case of obviousness with
regard to the claimed subject matter.
The examiner cites Dashiell for the teaching of a shared
memory multiprocessor having a plurality of processors, I/O
devices and cache memories connected to a bus. However, as
the examiner recognizes, Dashiell does not disclose that the
bus is a packet switched bus, as claimed by appellants.
Accordingly, the examiner relies on Baxter for the suggestion
Appeal No. 95-4096
Application No. 08/188,660
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of a desirability to use a packet switched bus for bursty or
high speed data transfer and optimum utilization of resources.
The examiner then concludes that it would have been obvious to
use a packet switched bus in Dashiell in order “to achieve
efficient bursty or high speed data transfer and optimizing
the utilization of resources as suggested by Baxter” [answer-
page 5].
It is our view that the skilled artisan would not have
been led to substitute a packet switched bus for the MBUS 29
of Dashiell. Dashiell discloses a very specific system for
maintaining data consistency among distributed processors
wherein a cache memory associated with each processor accesses
data from another cache, if needed, or from real memory. When
a processor writes into a data word in the cache, the cache
will update all other caches that share the data before
allowing the write to the local cache. Thus, once a cache
gets control of the bus in Dashiell, it does not relinquish
control until all other caches have been updated, at which
time the cache releases the MBUS and writes data into its own
cell, setting its own master flag and updating its own LRU
stack [column 9, lines 23-28].
Appeal No. 95-4096
Application No. 08/188,660
8
If one were to substitute, for whatever reason, a packet-
switched bus for the MBUS of Dashiell, Dashiell’s operation
would appear to be inoperable. The data consistency sought by
Dashiell would not be achieved by the use of a packet-switched
bus since, as explained by Baxter, at column 5, lines 28-31,
“a packet-switched bus is a bus whose bandwidth is allocated
on a demand basis, as opposed to a circuit-switched bus, whose
bandwidth is allocated for the duration of the connection.”
Since the bus of Dashiell is not a packet-switched bus,
extensive modification of Dashiell would be necessary in order
to derive any operable system, such modification constituting
invention itself, wherein data consistency is maintained while
employing a packet-switched bus. This, of course, is
appellants’ invention.
Further, since Baxter is not concerned at all with the
use of cache memories or the maintenance of data consistency,
there seems to be no reason for the artisan to have been led
to employ the packet-switched bus of Baxter in a shared memory
multiprocessor system for maintaining data consistency. Where
is the suggestion to so employ Baxter’s packet-switched bus?
A mere reference, by Baxter [column 1, lines 16-17], to such a
Appeal No. 95-4096
Application No. 08/188,660
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bus being an efficient transfer medium for bursty, or high
speed, data appears to be a weak motivation for attempting to
use a packet-switched bus in Dashiell when Dashiell does not
indicate that the data therein is high speed data of the type
of interest in Baxter and there is no indication that the
system of Dashiell would work with a packet-switched bus. The
examiner fails to take into account that the completely
different types of buses do not easily permit the substitution
of one for the other without an attendant, more-than-routine,
modification of other parts of the system.
Instant claim 2 clearly calls for the transactions
comprising “a request packet followed at an indeterminate
later time by a reply packet...” Clearly, the Dashiell system
operates in a completely different manner. There is no
request packet therein which is followed at an indeterminate
later time by a reply packet.
Appeal No. 95-4096
Application No. 08/188,660
10
The examiner’s decision rejecting claims 2 through 4
under both 35 U.S.C. 112, second paragraph, and under 35
U.S.C. 103 is reversed.
REVERSED
KENNETH W. HAIRSTON )
Administrative Patent Judge)
)
)
)
ERROL A. KRASS ) BOARD OF
PATENT
Administrative Patent Judge) APPEALS AND
) INTERFERENCES
)
)
MICHAEL R. FLEMING )
Administrative Patent Judge)
Appeal No. 95-4096
Application No. 08/188,660
11
Ronald Zibelli
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