Transcript Benchmarking SpaceWire Networks

International SpaceWire Conference 2007
17-19 September 2007
Benchmarking
SpaceWire Networks
Asaf Baron, Isask'har Walter, Ran Ginosar, Isaac Keslassy
EE Department, Technion, Haifa, Israel
Ofer Lapid
Israel Ministry of Defense
The problem
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Multiple proposals for SpaceWire
Vendors design new SpaceWire parts
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BUT …
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How can we evaluate proposals?
How can we compare parts from different
vendors?
Benchmark
Benchmark purposes
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Evaluate protocol proposals
Compare network configurations
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Cost
Performance
Reliability
Compare components
Formalize requirements
Improve the standard
Benchmark Contents
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End units
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Redundancy
Traffic specifications
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Unit X sends to unit Y
Quality of Service Requirements
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Bandwidth, real time constraints, deadlines,
Priorities, etc.
Benchmark does NOT include
implementation details
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No topology, no specific components
End units (examples)
Unit
#
#
Active
Units
Units
Data Handling System (DHS)
2
1
Reconfiguration Unit (RU)
1
1
Payload Sensor (Camera)
3
1
Downlink
2
1
Solar Cells Control
2
1
Star Tracker
3
3
Traffic matrix
Traffic matrix (examples)
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High bandwidth
From
Sensor
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To
Type
BW
B/sec
Storage
Payload
100M
Latency
Recommended
Priority
L
Low bandwidth
DHS
Sensor
Control
1000
Low
H
Using
the
Benchmark
Evaluating SpaceWire features
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Standard: Packet-level priority (PLP)
Non-Standard: N-Char interleaving (NCI)
N-Char Interleaving
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Not in SpaceWire standard
But, Very useful in Wormhole networks
Requires multiple VCs
VC code added to each N-Char
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Ideally, SPW would allow longer flits
No-NCI Example
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
66
68
70
72
74
76
78
80
10
12
14
16
18
2
4
6
8
0
100 Mb/s
Delay
Red:
26
Yellow:
48
Green:
69
400 Mb/s
Router #1
Router #2
400 Mb/s
NCI Example (4 VC)
Delay
93.6
86.4
88.8
74.4
76.8
79.2
62.4
64.8
67.2
69.6
50.4
52.8
55.2
57.6
38.4
40.8
43.2
45.6
33.6
26.4
28.8
14.4
16.8
19.2
21.6
91.2
81.6
31.2
2.4
4.8
7.2
9.6
24
96
84
72
60
48
36
12
0
100 Mb/s
Red (26):
31
Yellow (48):
38
Green (69):
45
400 Mb/s
Router #1
Router #2
400 Mb/s
Network topology
downlink
DHS
router
sensor
storage
Only active units shown and simulated
Redundant units, routers, links hidden and ignored
Simulator display
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Simulated using OPNET
A commercial simulator for networks
Simulations: Low priority payload traffic
1. SIMPLE NET
4. NCI+PLP
2. ADD PLP
5. NCI+PLP,
more VCs
3. ADD NCI
Simulations Results – Other Priorities
High Priority
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Medium Priority
NCI with PLP is beneficial
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Low ETE delay of med+high priority packets
High ETE delay of low priority packets
Summary
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A new SpaceWire benchmark (open source)
A new simulator for SpaceWire
An example of using the benchmark
Priorities help
Non-standard NCI helps even more