Cilk-NOW

1
Cilk-NOW

• ?????
• ????

Adaptive and Reliable Parallel Computing on
Networks of Workstations Robert D. Blumofe
(Univ. of Texas) Philip A. Lisiecki (MIT)
Proceedings of the USENIX Annual Technical
Conference, 1997
2
Cilk??

• C??????????????????????????
• DAG??????

3
Cilk-NOW

• ???PC??Cilk???????????????????
• ???Cilk
• PC????????????????
• ????

4
?????

• Cilk??
• ???
• work stealing??????
• ??????
• PC?????????
• ????
• ???????????
• ???

5
thread Fib (cont int k, int n) if (n lt2)
send_argument (k,n) else cont int x, y
spawn_next Sum (k, ?x, ?y) spawn Fib (x,
n-1) spawn Fib (y, n-2) thread Sum (cont
int k, int x, int y) send_argument (k, xy)
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Cilk??? (1/3)

• spawn T (args )
• spawn_next T (args )
• ??????T??????
• ?????????????closure???

Sum
0
Fib
Join counter
0
k
??Argument slots
??Argument slots
k
Arguments
Arguments
n9
?Join counter??Argument slots?(0?????)
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Cilk??? (3/3)

• cont
• continuation
• ??empty argument slot????
• ?closure???????
• argument slot???????????

Sum
2
k
continuation
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Cilk??? (2/3)

• send_argument(k, value)
• continuation k??????argument slot?value???

9
???
10
???
11
???
Sum
1
k
21
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???
Sum
0
k
21
13
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work stealing?????? (1/3)

• ?????? ready deque???
• ?????closure??????
• join counter?0????closure? deque????????
• deque????????????

14
work stealing?????? (2/3)

• ready deque??????work stealing????
• thief??????victim???
• steal request?victim???
• victim?
• ready deque???????,deque????closure?thief???
• ready deque????,thief????????

????thief ?????victim
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work stealing?????? (3/3)

• ?????closure???????
• ?????????????
• ???closure????spawn???????
• ????closure?????work???
• ????????????,???work????
• ??????????
• ??3???????????

16
work stealing??? (1/3)

• DAG??????

sequential execution spawn spawn_next continuation
instruction thread procedure
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work stealing??? (2/3)

• well structured?????
• ???procedure?????????
• ??,?????procedure?????thread??????

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work stealing??? (3/3)

• well structured?????????
• T1/P T8????????
• ? P ?????
• T1 DAG??instruction?
• (1????????????)
• T8 DAG??????
• (critical path?)

DAG??critical path???closure?, ready
deque?????????????????
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??????

• ???PC??(???)Cilk????????????????
• PC???,???????????????

????? A
????? C
????? B
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???????????

• ????????????,
• ????????closure???
• ?????????,
• ?closure??????????
• ??????continuation???????

?waiting closure???????????
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???????????

• work stealing?????
• subcomputationresult closure???
• ??????
• subcomputation???

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work stealing????? (1/5)

• subcomputation
• ready, waiting, assigned pool???????
• global?unique?name???
• PC?local?unique???
• work steal???????

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work stealing????? (2/5)

• thief?,
• subcomputation???
• steal??????victim???

victim s
thief r
subcomputation si
assigned
waiting
ready
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work stealing????? (3/5)

• victim?,
• ready pool?????subcomputation?round-robin???
• ready pool????closure?assigned pool???
• thief????thief?subcomputation??????

victim s
thief r
subcomputation si
assigned
waiting
ready
25
work stealing????? (3/5)

• victim?,
• ready pool?????subcomputation?round-robin???
• ready pool????closure?assigned pool???
• thief????thief?subcomputation??????

thief name
victim s
thief r
thief subcomp.
subcomputation si
assigned
waiting
ready
r rj
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work stealing????? (4/5)

• victim??thief?closure???
• thief?victim worker??????
• thief?result closure???
• ?????closure??continuation?,
• result closure????????????

victim s
thief r
subcomputation si
assigned
waiting
ready
r rj
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work stealing????? (5/5)

• 3??pool???????????

victim s
thief r
s
subcomputation si
assigned
waiting
ready
r rj
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work stealing????? (5/5)

• 3??pool???????????

victim s
thief r
subcomputation si
assigned
waiting
ready
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??????

• subcomputation???
• subcomputation?serialize
• continuation???
• ?????????,
• victim worker?????????
• victim closure??thief subcomputation???
• assigned pool?????thief worker?????????
• victim worker name???

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??????
worker t
subcomputation tk
assigned
waiting
ready
s si
worker s
worker u
t
subcomputation si
assigned
waiting
ready
r rj
worker r
s
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??????
worker t
subcomputation tk
assigned
waiting
ready
s si
worker s
worker u
worker u
t
subcomputation si
assigned
waiting
ready
r rj
worker r
s
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??????
worker t
subcomputation tk
assigned
waiting
ready
s si
worker u
worker s
t
subcomputation si
assigned
waiting
ready
r rj
worker r
s
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????

• PC????????????????????????????
• ?subcomputation????
• ???????????

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subcomputation???? (1/2)

• subcomputation?????????subcomputation???????????
• subcomputation??????return value?????
• ?well-structured???????
• transaction?????
• return value?????????commit

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subcomputation???? (2/2)

• ?????????,
• ????subcomputation???continuation???subcomputation
  ?abort
• abort??subcomputation???continuation???subcomputat
  ion?abort
• ????subcomputation??????continuation???subcomputat
  ion?,????subcomputation????

? PC????????????
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worker t
???
subcomputation tk
assigned
waiting
ready
s si
worker s
t
subcomputation si
assigned
waiting
ready
r rj
worker r
s
abort
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???????????

• ?????????????
• c.f.)DAG???????subcomputation????
• subcomputation????????????

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????

• ?????Cilk-NOW?????????
• SilkRoad2000
• Cilk-NOW SoftwareDSM
• Satin2001
• ???????????Scheduling??
• Concert2002
• ??????????????????

39
???

• ???PC??Cilk???????????????????
• ???Cilk
• PC????????????????
• ????

40
?????

• thiefvictim???????????
• ???????????????????
• ????????
• ??????????????????
• ????????????????