VIP Scheduler - INESC-ID

Fine-grained transaction scheduling
Hugo Rito and João Cachopo
WTM 2013
INESC-ID Lisboa
April 14th, 2013
1

Atention
DISCLAIMER
This is still a work in progress
The information contained in this
presentation is subject to change and
may not represent the final product
2

Introduction
Previously on...
S TM
SS TM
ATOM
S TM
3

Introduction
Software Transactional Memory
S TM
4

Introduction
STMBench7: 10% Writes + Small transactions
25
Speedup (No-STM single-thread)
20
15
10
5
JVSTM
0
1 4 8 12 16 20 24 28 32 36 40 44 48
# Threads
5

Introduction
STMBench7: 10% Writes + Long transactions
2.5
Speedup (No-STM single-thread)
2
1.5
1
0.5
JVSTM
0
1 4 8 12 16 20 24 28 32 36 40 44 48
# Threads
6

Introduction
Green STM
S TM =
S TM +
7

Introduction
FlashbackSTM
S TM
SS TM
ATOM
S TM
8

Introduction
STMBench7: Read-dominated + Long transactions
2.5
Speedup (No-STM single-thread)
2
1.5
1
0.5
0
JVSTM
FlashbackSTM
1 4 8 12 16 20 24 28 32 36 40 44 48
# Threads
9

Introduction
STMBench7: Read-dominated + Long transactions
Restart rate (%)
90
80
70
60
50
40
30
20
10
0
FlashbackSTM
JVSTM
1 4 8 12 16 20 24 28 32 36 40 44 48
# Threads
9

S TM
Transaction Scheduling
And now the
continuation...
S TM
ATOM
S TM
Scheduling
10

Transaction Scheduling
Scheduling
Reduce Conflicts
Monitor contention
Serialize transactions
11

Transaction Scheduling
Scheduling
No Scheduler
11

Transaction Scheduling
Scheduling
No Scheduler
Serializing Scheduler
11

Transaction Scheduling
Related work
CAR
Optimistic
Pessimistic
ATS
Shrink
No Conflicters
12

Transaction Scheduling
FlashbackSTM
FlashbackSTM
JVSTM + Memo
RO never conflict
RW conflicts vs. already committed
Early aborts
13

Transaction Scheduling
FlashbackSTM + Scheduling
2.5
Speedup (No-STM single-thread)
2
1.5
1
0.5
0
Shrink + FbSTM
CAR + FbSTM
No_Conflicters + FbSTM
ATS + FbSTM
FbSTM
1 4 8 12 16 20 24 28 32 36 40 44 48
# Threads
13

Transaction Scheduling
FlashbackSTM + Scheduling
Over serialization
Serialize non-conflicting transactions
Hinders parallelism
13

Transaction Scheduling
FlashbackSTM + Scheduling
No Scheduler
Serializing Scheduler
13

Transaction Scheduling
FlashbackSTM + Scheduling
CAR
Optimistic
?
Pessimistic
ATS
Shrink
No Conflicters
13

Proposal
VIP scheduler
VIP Scheduler
Optimistic (more)
Fine-grained
VIP transactions
14

Proposal
VIP execution
VIP Scheduler
E
E
E X P E E
VIPs
15

Proposal
VIP execution
VIP Scheduler
E
E
E X P E E
VIPs
E X
P
15

Proposal
VIP execution
VIP Scheduler
E
E
E X P E E
VIPs
E X
P
15

Proposal
VIP execution
VIP Scheduler
E E X X
E X P E E E X P
VIPs
E X
P
15

Proposal
VIP execution
VIP Scheduler
E E X X
E X P E E E X P E E
VIPs
15

Proposal
VIP execution
VIP Scheduler
E E X X
E X P E E E X P E E
V I P P R S
VIPs
15

Experimental Results
STMBench7: 10% Writes + Long transactions
Speedup (No-STM single-thread)
4
3.5
3
2.5
2
1.5
1
0.5
0
VIP + FbSTM
Shrink + FbSTM
CAR + FbSTM
No_Conflicters + FbSTM
ATS + FbSTM
FbSTM
1 4 8 12 16 20 24 28 32 36 40 44 48
# Threads
16

Experimental Results
STMBench7: 40% Writes + Long transactions
Speedup (No-STM single-thread)
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
VIP + FbSTM
Shrink + FbSTM
CAR + FbSTM
No_Conflicters + FbSTM
ATS + FbSTM
FbSTM
1 4 8 12 16 20 24 28 32 36 40 44 48
# Threads
17

Experimental Results
STMBench7: 90% Writes + Long transactions
Speedup (No-STM single-thread)
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
VIP + FbSTM
Shrink + FbSTM
CAR + FbSTM
No_Conflicters + FbSTM
ATS + FbSTM
FbSTM
1 4 8 12 16 20 24 28 32 36 40 44 48
# Threads
18

Future work
Challenges: Thread inactivity
Execution vs. Wait time
57 43
19

Future work
Challenges: Early aborts + Expected read-set
E X
P
20

Future work
Challenges: Early aborts + Expected read-set
E X
P
E C
20

Future work
Challenges: Early aborts + Expected read-set
E X
P
E C
T E D
20

Future work
Challenges: Set intersection
Read-set
?
Write-set
21

Q&A
Thank you,
Q U
E
S T I O N
S
22