speculation

Version 0.5.1 revision 0 uploaded 2010-06-27T22:18:27.000Z by EdwardKmett.

Package meta

Synopsis

A framework for safe, programmable, speculative parallelism

Description

A framework for safe, programmable, speculative parallelism, loosely based on http://research.microsoft.com/pubs/118795/pldi026-vaswani.pdf

This package provides speculative function application and speculative folds. And speculative STM actions take the place of the transactional rollback machinery from the paper.

For example:

spec g f a evaluates f g while forcing a, if g == a then f g is returned, otherwise f a is evaluated and returned. Furthermore, if the argument has already been evaluated, we skip the f g computation entirely. If a good guess at the value of a is available, this is one way to induce parallelism in an otherwise sequential task. However, if the guess isn't available more cheaply than the actual answer, then this saves no work and if the guess is wrong, you risk evaluating the function twice.

The best-case timeline looks like:

[---- f g ----]
   [----- a -----]
[-- spec g f a --]

The worst-case timeline looks like:

[---- f g ----]
   [----- a -----]
                 [---- f a ----]
[------- spec g f a -----------]

Compare these to the timeline of f $! a:

[---- a -----]
             [---- f a ----]

specSTM provides a similar time table for STM actions, but also rolls back side-effects.

Changes in 0.5.1:

• Exposed unsafeGetTagBits and unsafeIsEvaluated

Author

Edward A. Kmett

Bug reports

n/a

Category

Concurrency

Copyright

(c) 2010 Edward A. Kmett

Homepage

http://github.com/ekmett/speculation

Maintainer

Edward A. Kmett <ekmett@gmail.com>

Package URL

n/a

Stability

experimental

Components

• lib:speculation