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Re: RFE: "git bisect reverse"

From
EWEaldwulf Wuffinga <ealdwulf@googlemail.com>
Date
May 31, 2009, 22:18 UTC
Message-ID
<efe2b6d70905311518w4c2d79ecy8cdabd15a8effc7c@mail.gmail.com>
In-Reply-To
<4A1F07FA.6040008@zytor.com>
On Thu, May 28, 2009 at 10:54 PM, H. Peter Anvin <hpa@zytor.com> wrote:
Show 6 quoted lines
> How about simply modelling it linearly, with 100% probability for known
> skip point, 0% for a known good/bad point, and a linear gradient in
> between?  It's probably a good enough model.  In practice, it will
> vastly overestimate the probability of a skip, so if a linear model
> turns out to be too conservative, I would probably just try to model it
> as a higher-order power function.
Sounds plausible. It's not obvious how to generalise it to a DAG, though.

What's easier to implement is simple geometric decay (from a probability of 1 at the commit of an actual skip). It even has a plausible rationale - the probability that someone notices the brokenness and fixes it is probably a constant, which would lead to geometric decay. That probably doesn't reflect what happens when someone breaks a whole swath of stuff retrospectively somehow, though.

I've implemented geometric (and arithmetic) decay in bbchop, with a configurable decay factor. With a factor sufficiently close to one (eg, 0.99) it can be persuaded to hop a reasonable distance, which seems to scale to a certain extent with the number of commits left, so hopefully it won't be necessary to fiddle with the factor a lot.

http://github.com/Ealdwulf/bbchop/tree/master
Ealdwulf
Previous: H. Peter AnvinNext: Christian Couder
Message 15 of 18 in “RFE: "git bisect reverse"”
  1. H. Peter AnvinMay 26, 2009
  2. Sam VilainMay 27, 2009
  3. H. Peter AnvinMay 27, 2009
  4. Christian CouderMay 27, 2009
  5. Ealdwulf WuffingaMay 27, 2009
  6. Clemens BuchacherMay 27, 2009
  7. Ealdwulf WuffingaMay 27, 2009
  8. Sam VilainMay 27, 2009
  9. Ealdwulf WuffingaMay 28, 2009
  10. Sam VilainMay 29, 2009
  11. Ealdwulf WuffingaMay 31, 2009
  12. H. Peter AnvinMay 28, 2009
  13. Ealdwulf WuffingaMay 28, 2009
  14. H. Peter AnvinMay 28, 2009
  15. Ealdwulf WuffingaMay 31, 2009
  16. Christian CouderMay 27, 2009
  17. Nanako ShiraishiMay 27, 2009
  18. Matthieu MoyMay 27, 2009

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