|| ||Arjan van de Ven <email@example.com> |
|| ||firstname.lastname@example.org |
|| ||[PATCH 0/2] Some improvements to the cpuidle menu governor |
|| ||Sun, 9 May 2010 16:02:42 -0700|
|| ||Article, Thread
two patches to the menu governor that, together, boost the quality of
the decisions it makes significantly (results below).
The first patch is basically a bugfix, while the second patch adds some
smarts to the algorithm.
Both patches only impact the idle-duration predictor (for those
unfamiliar with the menu governor, the menu governor first tries to
predict the idle duration, and then uses a set of heuristics to pick
a suitable idle state based on this prediction. The better the
prediction the better the decision ends up being)
To show the quality of the predictor, I added some instrumentation
where I had perf report out the result of the current, after patch 1
and after patch 2 prediction value as well as the actual idle duration
as measured at the end of the idle period. The test run I give below had
69854 samples (other runs had pretty much the same result).
The quality indicator I use is the percentage of samples for which the
prediction is within a certain factor of the actual duration.
Factor before patches patch 1 patch 1+2
1.5x 29.1% 30.4% 34.1%
2x 33.6% 49.3% 52.9%
4x 43.6% 73.6% 75.2%
10x 56.9% 86.1% 86.5%
100x 78.4% 97.0% 97.2%
Arjan van de Ven Intel Open Source Technology Centre
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