Hi all,
> > >>
> > >> Can you continue your bisection using 'git bisect'? You've already
> > >> narrowed it down between 4.0 and 4.1, so you're well on your way.
> > >>
> > >
> > > OK - done.
> > > And finally I was successful!
> > > The following git commit is the one that is causing the trouble
Hi Julia!
> > > Have you tested on a vanilla (non-RT) kernel? I doubt there is
> > > anything RT specific about what you are seeing, but it might be nice
> > > to get confirmation. Also, bisection would probably be easier if you
> > > confirm on a
> vanilla kernel.
> > >
> > > I find it unlikely
Hi Julia,
> Have you tested on a vanilla (non-RT) kernel? I doubt there is anything RT
> specific
> about what you are seeing, but it might be nice to get confirmation. Also,
> bisection
> would probably be easier if you confirm on a vanilla kernel.
>
> I find it unlikely that it's a kernel co
Hi all!
>
> Hi Julia,
>
> thanks for the detailed analysis!
> >
> > [...]
> > Okay, we finally received our wakeup event. We were expecting to be
> > woken up at 10024735653388ns, but were actually woken up at
> 10024735682387ns.
> >
> > 10024735682387 - 10024735653388 = 28999ns
> >
> > Our ti
Hi Julia,
thanks for the detailed analysis!
>
> [...]
> Okay, we finally received our wakeup event. We were expecting to be woken up
> at
> 10024735653388ns, but were actually woken up at 10024735682387ns.
>
> 10024735682387 - 10024735653388 = 28999ns
>
> Our timer fired ~29us late! But w
Hi Mitch,
> > >
> > > Although, to be clear, it isn't the fact that there exists 8
> > > threads, it's
> > that the device is
> > > firing all 8 interrupts at the same time. The time spent in hardirq
> > context just waking
> > > up all 8 of those threads (and the cyclictest wakeup) is enough to
>
Hi all,
>
> Although, to be clear, it isn't the fact that there exists 8 threads, it's
> that the device is
> firing all 8 interrupts at the same time. The time spent in hardirq context
> just waking
> up all 8 of those threads (and the cyclictest wakeup) is enough to cause your
> regression.
>
Hi all,
I noticed that with fairly new versions of the Linux kernel, the igb driver
causes huge latencies with the cyclictest in a RT_PREEMPT environment.
The root cause seems to be the number of interrupts that are used for the igb
NIC devices as multiple of these irqs may occur at the same time
