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Re: AAARGH bisection is hard (Re: [2.6.39 regression] X locks up hard right after logging in)

From
ALAndrew Lutomirski <luto@mit.edu>
Date
May 13, 2011, 13:39 UTC
Message-ID
<BANLkTinoGfj1NUzTveSH0vgwZczCaFr8HA@mail.gmail.com>
In-Reply-To
<BANLkTi=YDZa+BRaG90vJsjrT9VxgySrDRQ@mail.gmail.com>

[resend because the Android gmail client apparently generates HTML emails even for plain text]

On Thu, May 12, 2011 at 1:37 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote:

Show 25 quoted lines
> On Thu, May 12, 2011 at 10:15 AM, Andrew Lutomirski <luto@mit.edu> wrote:
>>
>> OK, this sucks.  In the course of bisecting this, I've hit two other
>> apparently unrelated bugs that prevent my from testing large numbers
>> of kernels.  Do I have two questions:
>>
>> 1. Anyone have any ideas from looking at the log?
>
> Nope, that doesn't look very helpful.
>
>> 2.  The !&$#@ bisection is skipping all over the place.  I've seen
>> 2.6.37 versions and all manner of -rc's out of order.
>
> That's the _point_ of bisection. It jumps around. You can start off
> trying to pick points on my development tree, but I only have a
> hundred merges or so. You're going to start delving into the actual
> development versions very quickly. And if you don't do it early,
> bisection is going to be much much slower, because it's not going to
> pick half-way points.
>
> So bisection works so well exactly because it picks points that are
> far away from each other, and you should just totally ignore the
> version number. It's meaningless. Looking at it just confuses you.
> Don't do it.
>

I actually had better results looking at the version number, saying "blech", and running git merge v2.6.38. (git bisect good gets a little confused if I feed it the merge result, but I can just lie.)

Anyway, I must have made a mistake somewhere. The regression is in drm (presumably i915) and it has a new thread now.

--Andy
Previous: Linus TorvaldsNext: Christian Couder
Message 5 of 18 in “AAARGH bisection is hard (Re: [2.6.39 regression] X locks up hard right after logging in)”
  1. Andrew LutomirskiMay 12, 2011
  2. Linus TorvaldsMay 12, 2011
  3. Johannes SixtMay 12, 2011
  4. Linus TorvaldsMay 12, 2011
  5. Andrew LutomirskiMay 13, 2011
  6. Christian CouderMay 13, 2011
  7. Andrew LutomirskiMay 13, 2011
  8. Andrew LutomirskiMay 13, 2011
  9. Linus TorvaldsMay 13, 2011
  10. Andrew LutomirskiMay 13, 2011
  11. Andrew LutomirskiMay 13, 2011
  12. Linus TorvaldsMay 13, 2011
  13. Johannes SixtMay 13, 2011
  14. Linus TorvaldsMay 13, 2011
  15. Johannes SixtMay 13, 2011
  16. Junio C HamanoMay 13, 2011
  17. Andrew LutomirskiMay 13, 2011
  18. Linus TorvaldsMay 13, 2011

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