Am 20.10.2014 10:27 schrieb Richard Weinberger <[email protected]>: > > On Sun, Oct 19, 2014 at 2:39 PM, Thomas Meyer <[email protected]> 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
