On 11/24/2016 08:00 PM, Anshuman Khandual wrote:
...

quoted

The current mechanisms work fine when we have one or two page sizes.
But, they start to get a bit muddled when we mix page sizes inside
one VMA.  For instance, the DAX folks were proposing adding a set of
fields like:

So DAX is only case which creates this scenario of multi page sizes in
the same VMA ? Is there any cases other than DAX mapping ?

Both file and anonymous huge pages.  No other ones in the core VM that I
can think of.

quoted

	DevicePages:
	DeviceHugePages:
	DeviceGiganticPages:
	DeviceGinormousPages:

I guess these are the page sizes supported at PTE, PMD, PUD, PGD level.
Are all these page sizes supported right now or we are just creating
place holder for future.

I know there are patches for PUD level support in DAX, but I don't think
they're merged yet.  There is definitely *not* support for PGD level
since we don't have such support in hardware on x86 as far as I know.

quoted

SwapPss:               0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Locked:                0 kB
Ptes@4kB:	      32 kB
Ptes@2MB:	    2048 kB

So in the left column we are explicitly indicating the size of the PTE
and expect the user to figure out where it can really be either at PTE,
PMD, PUD etc. Thats little bit different that 'AnonHugePages' or the
Shared_HugeTLB/Private_HugeTLB pages which we know are the the PMD/PUD
level.

Yeah, it's a little different from what we have.

quoted

The format I used here should be unlikely to break smaps parsers
unless they're looking for "kB" and now match the 'Ptes@4kB' instead
of the one at the end of the line.

Right. So you are dropping the idea to introduce these fields as you
mentioned before for DAX mappings.

 	DevicePages:
 	DeviceHugePages:
 	DeviceGiganticPages:
 	DeviceGinormousPages:

Right.  We don't need those if we have this patch.

quoted

 	if (page) {
 		int mapcount = page_mapcount(page);
+		unsigned long hpage_size = huge_page_size(hstate_vma(vma));

+		mss->rss_pud += hpage_size;
 		if (mapcount >= 2)
-			mss->shared_hugetlb += huge_page_size(hstate_vma(vma));
+			mss->shared_hugetlb += hpage_size;
 		else
-			mss->private_hugetlb += huge_page_size(hstate_vma(vma));
+			mss->private_hugetlb += hpage_size;
 	}
 	return 0;

Hmm, is this related to these new changes ? The replacement of 'hpage_size'
instead of huge_page_size(hstate_vma(vma)) can be done in a separate patch.

Yes, this is theoretically unrelated, but I'm not breaking this 3-line
change up into a different patch unless there's a pretty good reason reason.

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