Kernel 'bisection'

Chris cpollock at embarqmail.com
Mon Feb 16 01:49:40 UTC 2015


On Sun, 2015-02-15 at 13:46 -0800, NoOp wrote:
> On 02/14/2015 03:40 PM, Bob 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".
> 
> You might want to have a look at:
> 
> <https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1384342>
> (kernel messages intel_crtc_wait_for_pending_flips correlate to compiz hang)
> 
> I had one of these just last night (my commenta are in #60 & #61)
> 
> 
> 
> > 
> > 
> >> 
> >> 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.
> > 
> 
> 
> 
Thanks, did a search for 'wait_for_pending' in my 4121 hourly syslog
snippets and didn't find it. I'm just wanting someone in Ubuntu or at
freedesktop.org to tell me what needs done other than a 'kernel
bisection'. I loaded the newest 3.19* kernel Friday or yesterday, can't
remember but I think it also locked up on me. It must have as I removed
it and went back to the 3.13.0-45.

-- 
Chris
KeyID 0xE372A7DA98E6705C
31.11°N 97.89°W (Elev. 1092 ft)
19:46:44 up 1 day, 35 min, 1 user, load average: 0.28, 0.41, 0.43
Ubuntu 14.04.1 LTS, kernel 3.13.0-45-generic




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