From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: dave@sr71.net
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH -mm] mincore: apply page table walker on do_mincore() (Re: [PATCH 00/10] mm: pagewalk: huge page cleanups and VMA passing)
Date: Tue, 3 Jun 2014 12:22:01 -0400 [thread overview]
Message-ID: <538df62f.0acde50a.3a1b.7febSMTPIN_ADDED_BROKEN@mx.google.com> (raw)
In-Reply-To: <538DF0F1.5070104@sr71.net>
On Tue, Jun 03, 2014 at 08:59:45AM -0700, Dave Hansen wrote:
> On 06/02/2014 11:18 PM, Naoya Horiguchi wrote:
> > + /*
> > + * Huge pages are always in RAM for now, but
> > + * theoretically it needs to be checked.
> > + */
> > + present = pte && !huge_pte_none(huge_ptep_get(pte));
> > + for (; addr != end; vec++, addr += PAGE_SIZE)
> > + *vec = present;
> > + cond_resched();
> > + walk->private += (end - addr) >> PAGE_SHIFT;
>
> That comment is bogus, fwiw. Huge pages are demand-faulted and it's
> quite possible that they are not present.
No. hugetlbfs adopts prefault mechanism, which creates free hugepage
pool in advance and hugepage allocation is done from the pool,
The above comment claims this. But if we want to comment more precisely,
it should be like "Hugepages under user process are always in RAM and
never swapped out, but ...".
Thanks,
Naoya Horiguchi
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prev parent reply other threads:[~2014-06-03 16:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-02 21:36 [PATCH 00/10] mm: pagewalk: huge page cleanups and VMA passing Dave Hansen
2014-06-02 21:36 ` [PATCH 01/10] mm: pagewalk: consolidate vma->vm_start checks Dave Hansen
2014-06-02 21:36 ` [PATCH 02/10] mm: pagewalk: always skip hugetlbfs except when explicitly handled Dave Hansen
2014-06-02 21:36 ` [PATCH 03/10] mm: pagewalk: have generic code keep track of VMA Dave Hansen
2014-06-02 21:36 ` [PATCH 04/10] mm: pagewalk: add page walker for mincore() Dave Hansen
2014-06-02 21:36 ` [PATCH 05/10] mm: mincore: clean up hugetlbfs handling (part 1) Dave Hansen
2014-06-02 21:36 ` [PATCH 06/10] mm: mincore: clean up hugetlbfs handler (part 2) Dave Hansen
2014-06-02 21:36 ` [PATCH 07/10] mm: pagewalk: kill check for hugetlbfs inside /proc pagemap code Dave Hansen
2014-06-02 21:36 ` [PATCH 08/10] mm: pagewalk: add locked pte walker Dave Hansen
2014-06-02 21:36 ` [PATCH 09/10] mm: pagewalk: use new locked walker for /proc/pid/smaps Dave Hansen
2014-06-02 21:36 ` [PATCH 10/10] mm: pagewalk: use locked walker for /proc/pid/numa_maps Dave Hansen
2014-06-02 21:52 ` [PATCH 00/10] mm: pagewalk: huge page cleanups and VMA passing Naoya Horiguchi
[not found] ` <1401745925-l651h3s9@n-horiguchi@ah.jp.nec.com>
2014-06-02 21:53 ` Dave Hansen
2014-06-03 6:18 ` [PATCH -mm] mincore: apply page table walker on do_mincore() (Re: [PATCH 00/10] mm: pagewalk: huge page cleanups and VMA passing) Naoya Horiguchi
[not found] ` <1401776292-dn0fof8e@n-horiguchi@ah.jp.nec.com>
2014-06-03 15:55 ` Dave Hansen
2014-06-03 20:01 ` Naoya Horiguchi
2014-06-03 20:08 ` Naoya Horiguchi
[not found] ` <1401825676-8py0r32h@n-horiguchi@ah.jp.nec.com>
2014-06-03 20:33 ` Dave Hansen
2014-06-03 15:59 ` Dave Hansen
2014-06-03 16:22 ` Naoya Horiguchi [this message]
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