Kernel 'bisection'

Sun Feb 15 00:02:18 UTC 2015

On Feb 14, 2015 11:41 PM, "Bob" <ubuntu-qygzanxc at listemail.net> wrote:
>
> ** Reply to message from Chris <cpollock at embarqmail.com> on Sat, 14 Feb
2015
> 16:20:25 -0600
>
> > On Sat, 2015-02-14 at 13:42 -0500, Scott Blair wrote:
> > > On 02/14/2015 08:19 AM, Chris wrote:
> > > > On Sat, 2015-02-14 at 13:05 +0000, Peter Waller wrote:
> > > >> Briefly, bisection is a way of taking a long list of 1000's of
> > > >> changes, and arranging things so that you only have to test more
like
> > > >> 10 of them, because you test midpoints. (and 2^10 ~ 1000).
> > > >>
> > > >>
> > > >> More detail:
> > > >>
> > > >>
> > > >> http://alblue.bandlem.com/2011/07/git-tip-of-week-git-bisect.html
> > > >>
> > > >>
> > > >> On 14 February 2015 at 12:57, Liam Proven <lproven at gmail.com>
wrote:
> > > >>          On 14 February 2015 at 02:59, Chris <
cpollock at embarqmail.com>
> > > >>          wrote:
> > > >>          > Who can give me some pointers on doing a kernel
bisection on
> > > >>          either
> > > >>          > 3.13.0-35 or -36 kernels? Ever since one of those two
were
> > > >>          installed,
> > > >>          > I'm on -45 now, my system will lockup (black screen,
cursor
> > > >>          moves, but
> > > >>          > CTRL-ALT-F1 will not take me to a terminal log-in. This
is
> > > >>          the error I
> > > >>          > see - Feb 13 19:05:22 localhost kernel: [807775.808019]
> > > >>          > [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer
> > > >>          elapsed... render
> > > >>          > ring idle. I've reported this last year on Launchpad as
bug
> > > >>          -
> > > >>          >
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1402331
> > > >>          I've jumped
> > > >>          > through all the hoops that have been suggested there
except
> > > >>          doing a
> > > >>          > kernel bisection which seems to have me confused. I'm
really
> > > >>          getting a
> > > >>          > bit tired of these continued 'lockups'.
> > > >>
> > > >>
> > > >>          I have to ask. WTF is a "kernel bisection"?
> > > >>
> > > >>          You want to... cut your kernel in half? Is this some kind
of
> > > >>          Solomonic
> > > >>          judgement? Because, you know, like half a baby doesn't
work,
> > > >>          half a
> > > >>          kernel won't, either.
> > > >>
> > > > That, to me, is as clear as mud just as these instructions on doing
it
> > > > are - https://wiki.ubuntu.com/Kernel/KernelBisection I can't live
with
> > > > having these 'lockups' every 2-10 days, more or less and I say that
> > > > because it's so very random I have no idea what even triggers it.
> > > >
> > > >
> > > Chris, I just had a lock up about 3 minutes go. I saw that my memory
sky
> > > rocketed, physical 99% and swap 90%. Normally they run low. CPU was
> > > running normal when it happened. I was logging into a flash page when
it
> > > happened. The flash page finally crashed and everything went back to
> > > normal. I am using Ubuntu 14. 04 kernel 3.13.0-45-generic and Chrome
> > > 40.0.2214.111 64 bit. Don't know if this will help in your problem.
> > >
> > > --
> > >
> > > Scott Blair
> > >
> > > Save on back up time BackupDevice=Null
> > >
> > >
> > I've had flash crash a few times since the latest update. Did the system
> > 'lockup'?
>
> I have had my computer lockup twice the past few weeks.  I was not using a
> browser the last time the lockup occurred and don't remember what I was
doing
> the first time it locked up.
>
>
> > For instance I have my clock showing seconds when this happens
> > to me the screen locks up however all background operations such as
> > fetchmail, procmail, spamassassin and so forth continue to run.
>
> These are the symptoms I also see.  There are no screen updates and the
cursor
> moves but the system will not accept any other input and anything already
> running continues to run.
>
>
> > If you
> > didn't see that type of a lockup then it must have just been flash.
> > However you can check your syslog for kernel: [ 8248.820016]
> > [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer elapsed... render
> > ring idle to see if you have the same issue.
>
> The last time I had the system lockup I left it running over night to see
if
> anything would happen.  After a reboot I looked in the logs and could not
find
> anything that happened at the time the lockup  occurred.  Checking my
syslog I
> can not find the string "hangcheck".
>
>

Hi,
Late to this party I know, but whilst using another flavor (crunchbang) I
have experienced the same thing, diddnt check syslog, but did manage to log
in via ssh. Having done that I killed then restarted 'X' and all was good,
execpt the lost work and time.
My thinking is if you are fortunate enough to be able to log in remotely
during a 'lock up' then the use of top (or htop) and looking at the logs
etc may well yield more info easier than kernel messing.

Sorry to jump in after so much work with such a 'daft' idea ;)

Pete s

> >
> > On another note I just tried to regress to the 3.13.0-35 kernel, system
> > would boot but had no cursor and login screen didn't look right. Could
> > not login so I removed it.
> >
> > So basically I'm back to where I was before just waiting for someone
> > from either of the two bug reports to tell me what to do next and
> > waiting for the next lockup.
>
> --
> Robert Blair
>
> --
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