Kernel 'bisection'

Chris cpollock at embarqmail.com
Sat Feb 14 22:20:25 UTC 2015


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'? 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. 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.

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.

Chris

-- 
Chris
KeyID 0xE372A7DA98E6705C
31.11°N 97.89°W (Elev. 1092 ft)
16:12:47 up 5 min, 1 user, load average: 2.26, 1.14, 0.49
Ubuntu 14.04.1 LTS, kernel 3.13.0-45-generic




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