[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] DomU's network interface will hung when Dom0 running 32bit
On Tue, Oct 15, 2013 at 11:19:42PM +0800, jianhai luan wrote: [...] > >>>> > >>>>* time_after_eq(now, next_credit) -> false > >>>>* time_before(now, expires) -> false > >>>If now is placed in above environment, the result will be correct > >>>(Sending package will be not allowed until next_credit). > >>No, it is not necessarily correct. Keep in mind that "now" wraps around, > >>which is the issue you try to fix. You still have a window to stall your > >>frontend. > >Remember that time_after_eq is supposed to work even with wraparound > >occurring, so long as the two times are less than MAX_LONG/2 apart. > > Sorry for my misunderstand explanation. I mean that > * time_after_eq()/time_before_eq() fix the jiffies wraparound, so > please think about jiffies in line increasing. > * time_after_eq()/time_before_eq() have the range (0, MAX_LONG/2), > the judge will be wrong if out of the range. > > So please think about three kind environment > - expires now next_credit > --------time increases this direction ----------> > > - expires [next_credit now next_credit+MAX_LONG/2 > --------time increase this direction -----------> > > - expires next_credit next_credit+MAX_LONG/2 now > --------time increadse this direction ----------> > > The first environment should be netfront consume all credit_byte > before next_credit, So we should pending one timer to calculator the > new credit_byte, and don't transmit until next_credit. > > the second environment should be calculator the credit_byte because > netfront don't consume all credit_byte before next_credit, and > time_after_eq() do correct judge. > > the third environment should be calculator in time because netfront > don't consume all credit_byte until next_credit.But time_after_eq do > error judge (time_after_eq(now, next_credit) is false), so the > remaining_byte isn't be increased. > > and I work on the third environment. You know now > > next_credit+MAX_LONG/2, time_before(now, expire) should be > true(time_before(now, expire) is false in first environment) > > Thanks for staighten this out for me. I'm just too dumb for this, please be patient with me. :-) Could you prove that time_before(now, expire) is always true in third case? That's where my main cencern lies. Is it because msecs_to_jiffies always returns MAX_JIFFY_OFFSET (which is ((LONG_MAX >> 1)-1) ) at most? Wei. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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