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SubjectRE: [PATCH] cpu-topology: warn if NUMA configurations conflicts with lower layer
Date
> -----Original Message-----
> From: Valentin Schneider [mailto:valentin.schneider@arm.com]
> Sent: Monday, January 13, 2020 7:17 PM
> To: Zengtao (B); Morten Rasmussen
> Cc: Sudeep Holla; Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] cpu-topology: warn if NUMA configurations
> conflicts with lower layer
>
> On 13/01/2020 06:51, Zengtao (B) wrote:
> > I have tried both, this previous one don't work. But this one seems
> work
> > correctly with the warning message printout as expected.
> >
>
> Thanks for trying it out.
>
> > This patch is based on the fact " non-NUMA spans shouldn't overlap ",
> I am
> > not quite sure if this is always true?
> >
>
> I think this is required for get_group() to work properly. Otherwise,
> successive get_group() calls may override (and break) the sd->groups
> linking as you initially reported.
>
> In your example, for MC level we have
>
> tl->mask(3) == 3-7
> tl->mask(4) == 4-7
>
> Which partially overlaps, causing the relinking of '7->3' to '7->4'. Valid
> configurations would be
>
> wholly disjoint:
> tl->mask(3) == 0-3
> tl->maks(4) == 4-7
>
> equal:
> tl->mask(3) == 3-7
> tl->mask(4) == 3-7
>
> > Anyway, Could you help to raise the new patch?
> >
>
> Ideally I'd like to be able to reproduce this locally first (TBH I'd like
> to get my first suggestion to work since it's less intrusive). Could you
> share how you were able to trigger this? Dietmar's been trying to
> reproduce
> this with qemu but I don't think he's there just yet.

Do you have got a hardware platform with clusters?what's the hardware
Cpu topology?

Regards
Zengtao
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