From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: kirill@shutemov.name
Cc: Konstantin Khlebnikov <koct9i@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Wu Fengguang <fengguang.wu@intel.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Borislav Petkov <bp@alien8.de>,
gorcunov@openvz.org
Subject: Re: [PATCH 0/4] pagecache scanning with /proc/kpagecache
Date: Thu, 22 May 2014 17:02:39 -0400 [thread overview]
Message-ID: <537e6609.c9630e0a.682e.ffffc1bcSMTPIN_ADDED_BROKEN@mx.google.com> (raw)
In-Reply-To: <537e385d.8764b40a.0a1f.ffffabccSMTPIN_ADDED_BROKEN@mx.google.com>
On Thu, May 22, 2014 at 01:47:48PM -0400, Naoya Horiguchi wrote:
...
> > BTW, does everybody happy with mincore() interface? We report 1 there if
> > pte is present, but it doesn't really say much about the page for cases
> > like zero page...
>
> According to manpage of mincore(2),
> mincore() returns a vector that indicates whether pages of the calling process's vir‐
> tual memory are resident in core (RAM), and so will not cause a disk access (page
> fault) if referenced. ...
>
> so we can assume that the callers want to predict whether they will have
> page faults. But it depends on whether the access is read or write.
> So I think current mincore() is not enough to do this prediction precisely
> for privately shared pages (including zero page and ksm page).
> Maybe we need a new syscall to solving this problem.
Sorry, this is not correct, we can use upper bits of each vector to
show protection info of page table entry.
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next prev parent reply other threads:[~2014-05-22 21:03 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-21 2:26 Naoya Horiguchi
2014-05-21 2:26 ` [PATCH 1/4] radix-tree: add end_index to support ranged iteration Naoya Horiguchi
2014-05-21 8:21 ` Konstantin Khlebnikov
2014-05-21 19:26 ` Naoya Horiguchi
2014-05-21 2:26 ` [PATCH 2/4] fs/proc/page.c: introduce /proc/kpagecache interface Naoya Horiguchi
2014-05-21 2:26 ` [PATCH 3/4] tools/vm/page-types.c: rework on file cache scanning mode Naoya Horiguchi
2014-05-21 2:26 ` [PATCH 4/4] Documentation: update Documentation/vm/pagemap.txt Naoya Horiguchi
2014-05-21 22:42 ` [PATCH 0/4] pagecache scanning with /proc/kpagecache Andrew Morton
2014-05-22 2:19 ` Naoya Horiguchi
[not found] ` <537d5ee4.4914e00a.5672.ffff85d5SMTPIN_ADDED_BROKEN@mx.google.com>
2014-05-22 2:33 ` Andrew Morton
2014-05-22 9:50 ` Konstantin Khlebnikov
2014-05-22 10:36 ` Kirill A. Shutemov
2014-05-22 17:47 ` Naoya Horiguchi
2014-05-22 21:02 ` Naoya Horiguchi [this message]
2014-06-02 5:24 ` [RFC][PATCH 0/3] mm: introduce fincore() Naoya Horiguchi
2014-06-02 5:24 ` [PATCH 1/3] replace PAGECACHE_TAG_* definition with enumeration Naoya Horiguchi
2014-06-02 16:12 ` Dave Hansen
2014-06-02 16:37 ` Naoya Horiguchi
[not found] ` <1401727052-f7v7kykv@n-horiguchi@ah.jp.nec.com>
2014-06-02 16:45 ` Dave Hansen
2014-06-02 17:14 ` Naoya Horiguchi
2014-06-02 18:19 ` Dave Hansen
2014-06-02 18:48 ` Naoya Horiguchi
2014-06-02 21:16 ` Andrew Morton
2014-06-02 21:51 ` Naoya Horiguchi
2014-06-02 5:24 ` [PATCH 2/3] mm: introduce fincore() Naoya Horiguchi
2014-06-02 6:42 ` Christoph Hellwig
2014-06-02 14:19 ` Naoya Horiguchi
2014-06-02 7:06 ` Michael Kerrisk
2014-06-02 14:21 ` Naoya Horiguchi
2014-06-02 12:23 ` Kirill A. Shutemov
2014-06-02 14:52 ` Naoya Horiguchi
2014-06-02 16:11 ` Dave Hansen
2014-06-02 16:22 ` Naoya Horiguchi
2014-06-02 5:24 ` [PATCH 3/3] selftest: add test code for fincore() Naoya Horiguchi
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