From: Andrew Morton <akpm@linux-foundation.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Hugh Dickins <hughd@google.com>, Greg Thelen <gthelen@google.com>,
David Rientjes <rientjes@google.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Dave Hansen <dave.hansen@intel.com>,
Dan Williams <dan.j.williams@intel.com>, Jan Kara <jack@suse.cz>,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: make transparent hugepage size public
Date: Tue, 6 Dec 2016 13:37:11 -0800 [thread overview]
Message-ID: <20161206133711.3109e092d550adc68f2f369c@linux-foundation.org> (raw)
In-Reply-To: <877f7difx1.fsf@linux.vnet.ibm.com>
On Tue, 06 Dec 2016 14:37:54 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:
> Hugh Dickins <hughd@google.com> writes:
>
> > Test programs want to know the size of a transparent hugepage.
> > While it is commonly the same as the size of a hugetlbfs page
> > (shown as Hugepagesize in /proc/meminfo), that is not always so:
> > powerpc implements transparent hugepages in a different way from
> > hugetlbfs pages, so it's coincidence when their sizes are the same;
> > and x86 and others can support more than one hugetlbfs page size.
> >
> > Add /sys/kernel/mm/transparent_hugepage/hpage_pmd_size to show the
> > THP size in bytes - it's the same for Anonymous and Shmem hugepages.
> > Call it hpage_pmd_size (after HPAGE_PMD_SIZE) rather than hpage_size,
> > in case some transparent support for pud and pgd pages is added later.
>
> We have in /proc/meminfo
>
> Hugepagesize: 2048 kB
>
> Does it makes it easy for application to find THP page size also there ?
>
Probably that would be more logical. But I'm a bit concerned about
adding more stuff to /proc/meminfo from a performance point of view -
that file gets read from quite frequently and we've already put some
quite obscure things in there. Probably we whould be careful about
this.
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next prev parent reply other threads:[~2016-12-06 21:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-06 6:05 [PATCH] mm: make transparent hugepage size public Hugh Dickins
2016-12-06 9:07 ` Aneesh Kumar K.V
2016-12-06 15:14 ` Dave Hansen
2016-12-06 17:19 ` Kirill A. Shutemov
2016-12-06 19:27 ` Dave Hansen
2016-12-07 4:13 ` Hugh Dickins
2016-12-06 21:37 ` Andrew Morton [this message]
2016-12-07 7:50 ` Michal Hocko
2016-12-07 8:04 ` Vlastimil Babka
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