Ex Parte Serebrin et al

Patent Trial and Appeal Board

Mar 20, 2017

13185008 (P.T.A.B. Mar. 20, 2017)

United States Patent and Trademark Office
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O.Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
13/185,008 07/18/2011 Benjamin C. SEREBRIN A665 1506
36378 7590
VMWARE, INC.
DARRYL SMITH
3401 Hillview Ave.
PALO ALTO, CA 94304
EXAMINER
SAIN, GAUTAM
ART UNIT PAPER NUMBER
2135
NOTIFICATION DATE DELIVERY MODE
03/22/2017 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
ipteam @ vmware. com
ipadmin@vmware.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte BENJAMIN C. SEREBRIN and BHAVESH MEHTA
Appeal 2017-000378
Application 13/185,008
Technology Center 2100
Before THU A. DANG, ELENI MANTIS MERCADER, and
JASON M. REPKO, Administrative Patent Judges.
REPKO, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Appellants appeal under 35 U.S.C. § 134(a) from the Examiner’s
rejection of claims 15—17 and 21—37. App. Br. I.1 Claims 1—14 and 18—20
have been canceled. We have jurisdiction under 35 U.S.C. § 6(b).
We reverse.
1 Throughout this opinion, we refer to (1) the Final Action (“Final Act.”)
mailed May 21, 2015, (2) the Appeal Brief (“App. Br.”) filed January 15,
2016, (3) the Examiner’s Answer (“Ans.”) mailed July 28, 2016, and (4) the
Reply Brief (“Reply Br.”) filed September 28, 2016.
Appeal 2017-000378
Application 13/185,008
THE INVENTION
Appellants’ invention increases the granularity of dirty-bit
information in a hardware-assisted memory-management system. Spec. | 9.
Dirty bits indicate whether a memory page has been modified since the
system last committed the page’s contents to disk. Id. ^ 6. The invention
allocates an address range’s unused bits to increase the dirty-bit
information’s granularity. Id. 19. For example, the invention’s dirty-bit
information can refer to only half of a memory page—i.e., a section instead
of an entire page. Id. In this way, the invention increases dirty-bit
granularity without changing the default size for memory pages and with
minimal changes to existing hardware. Id.
Claim 15 is reproduced below with emphasis:
15. A method of backing up a virtual machine running in a
computer system having a memory management unit that
manages memory mappings using a first set of hierarchically-
arranged page tables for mapping guest virtual addresses to guest
physical addresses and a second set of hierarchically-arranged
page tables for mapping the guest physical addresses to machine
memory addresses, comprising:
scanning entries of first and second page tables in the
second set that reference a common machine memory page;
determining that a first section of the common machine
memory page is dirty based on the entry of the first page table
that references the common machine memory page and
determining that a second section of the common machine
memory page is not dirty based on the entry of the second page
table that references the common machine memory page;
performing an operation on the first section of the common
machine memory page to determine changes to data stored in the
first section of the common machine memory page while not
performing an operation on the second section of the common
machine memory page to determine changes to data stored in the
second section of the common machine memory; and
2
Appeal 2017-000378
Application 13/185,008
transmitting the changes to the data stored in the first
section of the common machine memory page to a backup
system.
THE REJECTIONS
The Examiner relies on the following as evidence:
Imamura US 6,381,686 B1 Apr. 30, 2002
Sept. 13, 2007
Jan. 1,2009
July 16, 2009
Jan. 6, 2011
Jan. 27, 2011
July 7, 2011
Apr. 26, 2012
Leveille US 2007/0214340 A1
Anderson US 2009/0006805 A1
Agesen US 2009/0182976 A1
Hohmuth US 2011/0004739 A1
Kegel US 2011/0023027 A1
Scales US 2011/0167196 A1
Srinivasan US 2012/0102135 A1
Claims 15—17, 24—26, and 31—33 are rejected under 35 U.S.C.
§ 103(a) as unpatentable over Scales, Agesen, Hohmuth, and Imamura.2
Ans. 2—6.
Claims 21, 28, and 35 are rejected under 35 U.S.C. § 103(a) as
unpatentable over Scales, Agesen, Hohmuth, Imamura, and Srinivasan. Ans.
Claims 22, 29,3 and 36 are rejected under 35 U.S.C. § 103(a) as
unpatentable over Scales, Agesen, Hohmuth, Imamura, Srinivasan, and
Kegel. Ans. 7—8.
2 The Examiner omits claims 24 and 31 from the rejection’s heading.
Ans. 2. This appears to be a harmless typographical error because, under
that heading, the Examiner provides a rejection for claims 24 and 31.
Id. at 6. So, for the purposes of this appeal, we treat claims 24 and 31 as
rejected over Scales, Agesen, Hohmuth, and Imamura.
3 The Examiner does not reject claim 29 using the Anderson reference
(Ans. 7—9), which is used in the rejection of parent claim 27 {id. at 9).
6-7.
3
Appeal 2017-000378
Application 13/185,008
Claims 23, 30, and 37 are rejected under 35 U.S.C. § 103(a) as
unpatentable over Scales, Agesen, Hohmuth, Imamura, Srinivasan, Kegel,
and Leveille. Ans. 8—9.
Claims 27 and 34* * * 4 are rejected under 35 U.S.C. § 103(a) as
unpatentable over Scales, Agesen, Hohmuth, Imamura, and Anderson.
Ans. 9.
THE OBVIOUSNESS REJECTION OVER SCALES, AGESEN,
HOHMUTH, AND IMAMURA
Contentions
The Examiner concludes that claim 15 would have been obvious in
view of a combination of Scales, Agesen, Hohmuth, and Imamura. Ans. 2—
5. In this proposed combination, the Examiner finds that Scales determines
whether sections of a common machine-memory page are dirty. Id. at 3.
According to the Examiner, the entries in Scales’s page table 210 correspond
to the recited entries. Id. (citing Scales Fig. 2, entry 290, table 210); see also
Ans. 11. To “further supplement” Scales (Ans. 12), the Examiner finds that
Hohmuth’s superpage corresponds to the recited common machine-memory
page. See id. at 4.
Because we do not sustain the rejection of independent claim 24, from which
claim 29 depends, the Examiner’s omission of the Anderson reference in the
claim 29’s rejection does not affect the outcome of this appeal.
4 In the heading for this rejection, the Examiner lists claim 30 as being
rejected. Ans. 9. Yet, under this heading, the Examiner provides a
substantive rejection for claim 34, not claim 30. See id. Claim 30 is rejected
separately, under a different rationale. See id. at 8—9. So, for the purposes
of this appeal, we treat claim 34 as rejected under 35 U.S.C. § 103(a) as
unpatentable over Scales, Agesen, Hohmuth, Imamura, and Anderson.
4
Appeal 2017-000378
Application 13/185,008
Appellants argue that the Examiner’s combination does not teach or
suggest the recited determining step. App. Br. 9-13; Reply Br. 2—5.
According to Appellants, in Scales and Hohmuth, the page table entries and
corresponding dirty bits refer to different pages, not sections of a common
page. App. Br. 11—12.
Appellants further contend that Hohmuth’s page table entries fail to
cure Scales’s deficiencies. Id. at 12. According to Appellants, the dirty bits
in Hohmuth’s superpage entries cannot be set in the recited manner—i.e.,
one dirty and another not dirty. Reply Br. 4. Rather, Appellants argue that
Hohmuth’s superpage entries must have the same dirty-bit setting. Id.
(citing Hohmuth 143).
Analysis
We agree with Appellants that the Examiner has not shown that
Scales and Hohmuth collectively teach or suggest:
determining that a first section of the common machine memory
page is dirty based on the entry of the first page table that
references the common machine memory page and determining
that a second section of the common machine memory page is
not dirty based on the entry of the second page table that
references the common machine memory page,
as recited in claim 15. See App. Br. 9—13; Reply Br. 2—5.
In the above-quoted limitation, claim 15 expressly requires (1) a
common machine-memory page with two sections and (2) two page tables
having entries that refer to this common page. Figure 3E illustrates one
embodiment and is shown below.
5
Appeal 2017-000378
Application 13/185,008
324i
Appellants’ Figure 3E shows tables 324j and 324i with entries referring
to a common machine memory page 325E having sections.
In the rejection, the Examiner finds that Scales determines whether a
memory page has been modified using dirty bits. Ans. 3 (citing Scales 5,
25, 26, 32, Figs. 2, 6). But the Examiner’s rejection only discusses entry
290, without identifying a second entry in Scales that is used in this
determination. Ans. 3.
Nor is it apparent from the cited paragraphs which entries in Scales
correspond to the two recited entries. See Scales Tflf 5, 25, 26, 32. Rather,
the cited paragraphs discuss “the page table entry” and “the dirty bit”—in
the singular—when discussing how to process one memory page. See, e.g.,
id. 125 (“. . . module 310 stores the . . . address corresponding to the page
table entry with the set dirty bit [to] transmit the memory page . . . .”)
(emphasis added); id. 126 (discussing “the dirty bit of a memory page”)
(emphasis added). On this record, we agree with Appellants (App. Br. 11)
6
Appeal 2017-000378
Application 13/185,008
that the Examiner has not identified two entries in Scales that refer to a
common page, as in the recited determination.
Although the Examiner finds that Scales teaches a common machine-
memory page in the determining step in one part of the rejection (Ans. 3),
the Examiner states elsewhere that Scales lacks a common machine-memory
page and cites Hohmuth in concluding that the claim would have been
obvious {id. at 4). The Examiner explains that Hohmuth is used to “further
supplement” Scales. Id. at 12. Nevertheless, Appellants argue that
Hohmuth also lacks the limitation at issue. App. Br. 12; Reply Br. 4. We
agree.
Unlike claim 15, Hohmuth’s Figure 3 shows page table 310 with
entries that refer to different pages, not two page tables referring to sections
of a common page as recited. See Hohmuth Fig. 3, cited in Ans. 12.
Hohmuth’s Figure 3 is shown below.
Hohmuth Figure 3 showing entries 301—318 in page table 310 referring
to pages 331—348.
7
Appeal 2017-000378
Application 13/185,008
To be sure, Hohmuth uses superpages corresponding to a set of pages.
Hohmuth || 8, 30, cited in Ans. 4. Unlike the recited entries, which have
different dirty-bit information, Hohmuth’s entries corresponding to a
superpage are subject to consistency requirements. Hohmuth 143, cited in
Ans. 4. In one cited example, Hohmuth requires that all superpage entries
be identical. Hohmuth 145, cited in Ans. 4. In another example, Hohmuth
examines the set of entries together to determine validity. Hohmuth 148,
cited in Ans. 4. In considering all superpage entries together, Hohmuth uses
a logical OR operation on the relevant bits of all entries to make a
determination for the entire superpage. Hohmuth 146. On this record, we
agree with Appellants’ contention (App. Br. 12; Reply Br. 4) that the
Examiner has not shown that Hohmuth determines whether a first and
second sections of the superpage are dirty using the individual entries.
The Examiner does not rely on the Agesen or Imamura references to
teach the determining step, which is missing from Scales and Hohmuth. See
Ans. 2—5. Therefore, Appellants’ arguments regarding Scales and Hohmuth
are dispositive, and we need not reach Appellants’ remaining arguments.
Appellants have persuaded us of error in the rejection of (1)
independent claim 15, (2) independent claims 24 and 31, which recite
commensurate limitations, and (3) dependent claims 16, 17, 25, 26, 32, and
33 for similar reasons.
THE OTHER OBVIOUSNESS REJECTIONS
We also do not sustain the Examiner’s rejections of dependent claims
21—23, 27—30, and 34—37 for the same reasons discussed above in
connection with independent claims 15, 24, and 31. The Examiner did not
8
Appeal 2017-000378
Application 13/185,008
rely on these additional references to teach the determining step, which is
missing from Scales and Hohmuth. See Ans. 6—9. Accordingly, these
references do not cure the deficiency explained previously.
DECISION
We reverse the Examiner’s rejection of claims 15—17 and 21—37.
REVERSED
9