Messages in this thread | | | Date | Mon, 16 Sep 2013 16:54:38 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 07/50] mm: Account for a THP NUMA hinting update as one PTE update |
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On Mon, Sep 16, 2013 at 09:39:59AM -0400, Rik van Riel wrote: > On 09/16/2013 08:36 AM, Peter Zijlstra wrote: > > On Tue, Sep 10, 2013 at 10:31:47AM +0100, Mel Gorman wrote: > >> A THP PMD update is accounted for as 512 pages updated in vmstat. This is > >> large difference when estimating the cost of automatic NUMA balancing and > >> can be misleading when comparing results that had collapsed versus split > >> THP. This patch addresses the accounting issue. > >> > >> Signed-off-by: Mel Gorman <mgorman@suse.de> > >> --- > >> mm/mprotect.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/mm/mprotect.c b/mm/mprotect.c > >> index 94722a4..2bbb648 100644 > >> --- a/mm/mprotect.c > >> +++ b/mm/mprotect.c > >> @@ -145,7 +145,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, > >> split_huge_page_pmd(vma, addr, pmd); > >> else if (change_huge_pmd(vma, pmd, addr, newprot, > >> prot_numa)) { > >> - pages += HPAGE_PMD_NR; > >> + pages++; > > > > But now you're not counting pages anymore.. > > The migrate statistics still count pages. That makes sense, since the > amount of work scales with the amount of memory moved.
Right.
> It is just the "number of faults" counters that actually count the > number of faults again, instead of the number of pages represented > by each fault.
So you're suggesting s/pages/faults/ or somesuch?
> IMHO this change makes sense.
I never said the change didn't make sense as such. Just that we're no longer counting pages in change_*_range().
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