[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] remove blocked time accounting from xen "clockchip"
>>> On 21.12.11 at 14:53, Laszlo Ersek <lersek@xxxxxxxxxx> wrote: > On 12/21/11 09:32, Jan Beulich wrote: >> I currently have no idea what the remain 1% could be attributed to, >> so thoughts from others would certainly be welcome. > > What about irqtime_account_process_tick() calling account_idle_time() > with "cputime_one_jiffy" -- it could more frequently trigger the > underflow in _cputime_to_cputime64(). In that case we might want to > decrease idle time (ie. account "negative" cputime against idle), but can't. Despite my thinking of this supposedly being impossible, I put in accounting of what is getting lost here. With an unexpected result: There's far more stolen ticks that can't get subtracted from one of the other counters than such that can. With the result that if I kept a record of how many still didn't get used for adjustment, there would then be about 10% under-accounting (instead on the 1% over- accounting). I understand this as meaning that the majority of stolen ticks don't get mis-accounted in any of the other counters, and it's just very few that need to be corrected for. But I'm not entirely convinced of this explanation. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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