Messages in this thread | | | Date | Tue, 1 Aug 2023 18:15:48 +0200 | Subject | Re: [PATCH v2 1/8] mm/gup: reintroduce FOLL_NUMA as FOLL_HONOR_NUMA_FAULT | From | David Hildenbrand <> |
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On 01.08.23 17:48, Peter Xu wrote: > On Tue, Aug 01, 2023 at 02:48:37PM +0200, David Hildenbrand wrote: >> @@ -2240,6 +2244,12 @@ static bool is_valid_gup_args(struct page **pages, int *locked, >> gup_flags |= FOLL_UNLOCKABLE; >> } >> >> + /* >> + * For now, always trigger NUMA hinting faults. Some GUP users like >> + * KVM really require it to benefit from autonuma. >> + */ >> + gup_flags |= FOLL_HONOR_NUMA_FAULT; > > Since at it, do we want to not set it for FOLL_REMOTE, which still sounds > like a good thing to have?
I thought about that, but decided against making that patch here more complicated to eventually rip it again all out in #4.
I fully agree that FOLL_REMOTE does not make too much sense, but let's rather keep it simple for this patch.
Thanks!
> > Other than that, looks good here. > > Side note: when I was looking at the flags again just to check the > interactions over numa balancing, I found FOLL_NOFAULT and I highly suspect > that's not needed, instead it just wants to use follow_page[_mask]() with > some proper gup flags passed over.. but that's off topic.
Be prepared for my proposal of removing foll_flags from follow_page() ;)
(accompanied by a proper documentation)
Especially as we have FOLL_PIN users of FOLL_NOFAULT, follow_page() is a bad fit.
-- Cheers,
David / dhildenb
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