1. EECS 582 Midterm Review
Mosharaf Chowdhury
EECS 582 – W16

2. Stats on the 18 Reviewers
EECS 582 – W16

3. Stats on the 21 Papers We’ve Reviewed
EECS 582 – W16

4. Stats on the 21 Papers We’ve Reviewed
EECS 582 – W16

5. Classics
EECS 582 – W16

6. Classics UNIX System R (Arguably) the first commodity OS
Simplicity is king when you must support diverse applications
Everything is a file!
System R
The first relational database implementation
Design iteratively and be ready to throw away
Find the “right” metric and do everything when you must deliver performance (i.e., specialization instead of generalization)
EECS 582 – W16

7. Storage and File Systems
EECS 582 – W16

8. Storage and File Systems
RAID
Industry standard for durable, high-performance storage
Parallelize for performance and fault-tolerance
FFS
Improved UNIX’s default file systems
Be aware of and exploit hardware characteristics
JFS
Provides crash recovery to file systems
Log what you’ll do before you do it!
EECS 582 – W16

9. Kernels
EECS 582 – W16

10. Kernels Exokernel Multikernel
Minimal kernel instead of a full-fledged one
End-to-end argument: only provide services that everyone needs to balance between specialization (performance) and generalization (applicability)
Multikernel
Make communication explicit when you must communicate
Shared-nothing design
EECS 582 – W16

11. Kernels IX
Separate control and data planes to provide I/O performance
Kernels aren’t inherently slow; it’s about how we do things
Commuter
Interfaces dictate scalable design
EECS 582 – W16

12. Virtual Memory and RPC
EECS 582 – W16

13. Virtual Memory and RPC Memory Coherence RPC
Shared-everything design requires frequent updates
Keeping things coherent is expensive but provides simple programming models
RPC
Makes distributed nature more explicit while keeping the same programming model as a non-distributed system
No shared memory
EECS 582 – W16

14. Concurrency and Scheduling
EECS 582 – W16

15. Concurrency and Scheduling
SEDA and Fibers
Thread- and event-based programming models both have their advantages and drawbacks (ease of programming vs. scalability and performance)
It is possible to find a balance between the two
Lottery and Stride Scheduling
Randomized and deterministic proportional scheduling
The key challenge is in determining the proportions (weights)
EECS 582 – W16

16. Reliability and Fault Tolerance
EECS 582 – W16

17. Reliability and Fault Tolerance
Eraser
Detecting bugs, specially the non-deterministic ones, is hard
Provide a “tight” coverage to allow manual inspection
Nooks
Failure is inevitable
Isolate it and start again
EECS 582 – W16

18. Virtual Machines
EECS 582 – W16

19. Virtual Machines Xen and ESX Live Migration ReVirt
Virtualization comes in many shapes and forms (e.g., full virtualization vs paravirtualization)
Choose the one that fits your requirements (e.g., performance, consolidation, deployability)
Fit for your workload
Live Migration
Keep things running until you must stop
ReVirt
Quis custodiet ipsos custodes? (Roman poet Juvenal in Satires)
It’s turtles all the way down!
EECS 582 – W16