Re: [lkp] [x86/MSI] 52f518a3a7c: -30.5% netperf.Throughput_tps

Thomas Gleixner
2015-06-16T06:13:52Z

On Tue, 16 Jun 2015, Jiang Liu wrote:

> On 2015/6/16 1:52, Thomas Gleixner wrote:
> > On Mon, 15 Jun 2015, Huang Ying wrote:
> >
> >> FYI, we noticed the below changes on
> >>
> >> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> >> commit 52f518a3a7c2f80551a38d38be28bc9f335e713c ("x86/MSI: Use hierarchical irqdomains to manage MSI interrupts")
> >>
> >
> > I really appreciate this testing effort, but the information provided
> > is not really helpful.
> >
> > I asked this before. Can you pretty please, upload ALL relevant
> > information (.config, full dmesg, below stats, /proc/interrupts ...)
> > to some place where everyone interested can download them?
> >
> > Then themail contains a useful link instead of 200k waste of network bandwidth.
>
> Hi Ying and Thomas,
> I guess this report discloses a regression in hierarchy
> irqdomain, and which should have been fixed by the patch posted at:
> lkml.org/lkml/2015/6/1/80
> The root cause is that, with hierarchy irqdomain enabled,
> there are multiple irq_data associated with one irq. And function
> irq_move_irq() on x86 uses a wrong copy of irq_data to check
> whether there's pending irq migration operation. So all irq migration
> /set_affinity operations will get pending for ever. This may
> affect network performance due to interrupt load balance issue.
> And the patch set posted at
> www.gossamer-threads.com/lists/linux/kernel/2185533
> should have solved all such regressions.

Next time, please send fixes which need to be applied right away
seperate from patch series which touch the world and some more.

Thanks,

tglx