Messages in this thread | | | Date | Mon, 20 Oct 2014 11:51:33 +0200 | Subject | Re: [uml-devel] [UM] Long loop in __getnsdayoftime() after resume from ram | From | Thomas Meyer <> |
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Am 20.10.2014 10:27 schrieb Richard Weinberger <richard.weinberger@gmail.com>: > > On Sun, Oct 19, 2014 at 2:39 PM, Thomas Meyer <thomas@m3y3r.de> wrote: > > Hello, > > > > in UML kernel I get a long cpu using loop in __getnstimeofday() > > (kernel/time/timekeeping.c:315) in the call of timespec_add_ns(), > > when I left the host kernel suspended to ram for a few hours and resume > > again. > > this is because it seems like the tk->xtime_sec wasn't updated yet, but > > the nsecs were. nsecs can be as high as 8111000111000111000l > > > > the function timespec_add_ns() (include/linux/time.h:266) will call > > __iter_div_u64_rem() which has an optimized loop for the case > > that the dividend is not much bigger as the divisior. > > but this isn't the case for resume from ram on the host kernel. > > > > any ideas how to fix this? is it possible to intercept the resume from > > ram and update the timekeeper->xtime_sec somehow? > > or can the um arch somehow overwrite timespec_add_ns() to always use > > div_u64_rem() instead? > > Hmm, does this always happen?
Yes, my single core system seems to trigger this every time after resume from ram.
> At least on my notebook it did not happen. I've started an UML yesterday > suspended it and after more than 12h it worked fine today. > > BTW: Do you see the issue also then freezing UML using the freezer cgroup?
I'm not sure what do you mean by this. Do I need to enable some special configs for this in the host or uml kernel?
> Would be easier to debug. :) > > -- > Thanks, > //richard
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