SLIDE 1
From Lock-Free to Wait-Free: Linked List Edward Duong Outline 1) - - PowerPoint PPT Presentation
From Lock-Free to Wait-Free: Linked List Edward Duong Outline 1) - - PowerPoint PPT Presentation
From Lock-Free to Wait-Free: Linked List Edward Duong Outline 1) Outline operations of the locality conscious linked list [Braginsky 2012] 2) Transformation concept from lock-free -> wait-free [Timnat 2014] Why Build Concurrent ADTs
SLIDE 2
SLIDE 3
Why Build Concurrent ADTs
- Leverage multi-cores for speed and throughput
i.e., how many operations can we perform at once
- Achieving performance guarantees for applications such as
real-time systems
SLIDE 4
Brief History
Wait-Free (WF) and Lock-Free (LF) ADTs:
1993 - Queue (WF) - Herlihy 1995 - Linked List (LF) - Valois 2002 - Hash Tables (LF) - Michael 2005 - B-Tree (LF) - Bender 2010 - Locality-conscious Linked List (LF) - Braginsky and Petrank 2012 - B+Tree (LF) - Braginsky and Petrank
SLIDE 5
Freedom!
Blocking
- Operations use heavy mutual exclusion
Increase in guarantees
Terminology from M. Herlihy [1988, 1990]
SLIDE 6
Freedom!
Blocking
- Operations are serialized
Obstruction-free
- Guaranteed to complete an operation if there is no contention
Increase in guarantees
Terminology from M. Herlihy [1988, 1990]
SLIDE 7
Freedom!
Blocking
- Operations are serialized
Obstruction-free
- Guaranteed to complete an operation if there is no contention
Lock-free
- Even with contention, at least one operation will succeed
Increase in guarantees
Terminology from M. Herlihy [1988, 1990]
SLIDE 8
Freedom!
Blocking
- Operations are serialized
Obstruction-free
- Guaranteed to complete an operation if there is no contention
Lock-free
- Even with contention, at least one operation will succeed
Increase in guarantees
Wait-free
- Even with contention, all operations are bounded
Terminology from M. Herlihy [1988, 1990]
SLIDE 9
Freedom!
Blocking
- Operations are serialized
Obstruction-free
- Guaranteed to complete an operation if there is no contention
Lock-free
- Even with contention, at least one operation will succeed
Wait-free
- Even with contention, all operations are bounded
=
Increase in throughput
Terminology from M. Herlihy [1988, 1990]
SLIDE 10
Linked List: Details
- Ordered list
- Stores key / data pairs; no duplicate keys
- Operations: Search, Insert and Delete
- Locality Conscious (optimized for cache)
SLIDE 11
Chunks
Virtual page ...
SLIDE 12
Chunks
SLIDE 13
Search(key)
- Search for key: 20
SLIDE 14
Search(key)
- Search for key: 20
SLIDE 15
Search(key)
- Search for key: 20
SLIDE 16
Search(key)
- Search for key: 20
SLIDE 17
Insert(key, data)
- Insert key 18 with data
3
SLIDE 18
Insert(key, data)
- Insert key 18 with data
3
SLIDE 19
Insert(key, data)
- Insert key 18 with data
3
SLIDE 20
Insert(key, data)
- Insert key 18 with data
3
SLIDE 21
Insert(key, data)
- Insert key 18 with data
3
SLIDE 22
Insert(key, data)
- Insert key 18 with data
3
SLIDE 23
Insert(key, data)
- Insert key 18 with data
3
SLIDE 24
Delete(key)
- Delete key 60
SLIDE 25
Delete(key)
- Delete key 60
SLIDE 26
Delete(key)
- Delete key 60
SLIDE 27
Delete(key)
- Delete key 60
SLIDE 28
Delete(key)
- Delete key 60
SLIDE 29
Delete(key)
- Delete key 60
SLIDE 30
Lock-Free -> Wait-Free
- Can we go from: At least one operation finishing after some
finite steps -> any operation is bounded by some finite number of steps? Recipe:
- Contention Counter
- Help Queue
- Modifications to: Search, Insert and Delete
SLIDE 31
Concept Behind Helping
Operation 1 Operation 2 Operation 3
SLIDE 32
Concept Behind Helping
Enqueue: Operation 1 Operation 2 Operation 3
SLIDE 33
Concept Behind Helping
Operation 1 Helping 1 Operation 3
SLIDE 34
Concept Behind Helping
Operation 1 Helping 1 Helping 1
SLIDE 35
Concept Behind Helping
Success Operation 4 Operation 5
SLIDE 36
Conclusions
- Adoption is on the rise!
- Libraries:
○ Boost ○ Noble (Swedish research group) ○ Amino Concurrent Building Blocks
SLIDE 37
Bibliography
- Braginsky, Anastasia, and Erez Petrank. "Locality-conscious lock-free linked lists." Distributed Computing and Networking. Springer
Berlin Heidelberg, 2011. 107-118.
- Timnat, Shahar, and Erez Petrank. "A Practical Wait-Free Simulation for Lock-Free Data Structures." (2014).
- Herlihy, Maurice. "A methodology for implementing highly concurrent data objects." ACM Transactions on Programming Languages
and Systems (TOPLAS) 15.5 (1993): 745-770.
- Valois, John D. "Lock-free linked lists using compare-and-swap." Proceedings of the fourteenth annual ACM symposium on Principles
- f distributed computing. ACM, 1995.
- Michael, Maged M. "High performance dynamic lock-free hash tables and list-based sets." Proceedings of the fourteenth annual ACM
symposium on Parallel algorithms and architectures. ACM, 2002.
- Bender, Michael A., Erik D. Demaine, and Martin Farach-Colton. "Cache-oblivious B-trees." Foundations of Computer Science, 2000.
- Proceedings. 41st Annual Symposium on. IEEE, 2000.
- Braginsky, Anastasia, and Erez Petrank. "A lock-free b+ tree." Proceedinbgs of the 24th ACM symposium on Parallelism in algorithms
and architectures. ACM, 2012.
- Herlihy, Maurice P. "Impossibility and universality results for wait-free synchronization." Proceedings of the seventh annual ACM
Symposium on Principles of distributed computing. ACM, 1988. Libraries: http://www.boost.org/doc/libs/1_53_0/doc/html/lockfree.html http://www.noble-library.org/ http://amino-cbbs.sourceforge.net/what-is-cbbs.html