From: Andrew Morton <akpm@linux-foundation.org>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: linux-mm@kvack.org, Wu Fengguang <fengguang.wu@intel.com>,
Pavel Emelyanov <xemul@parallels.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] page-types.c: support KPF_SOFTDIRTY bit
Date: Mon, 7 Oct 2013 17:50:16 -0700 [thread overview]
Message-ID: <20131007175016.a513865c5ecae4bd5759c2b0@linux-foundation.org> (raw)
In-Reply-To: <1380913335-17466-2-git-send-email-n-horiguchi@ah.jp.nec.com>
On Fri, 4 Oct 2013 15:02:15 -0400 Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> wrote:
> Soft dirty bit allows us to track which pages are written since the
> last clear_ref (by "echo 4 > /proc/pid/clear_refs".) This is useful
> for userspace applications to know their memory footprints.
>
> Note that the kernel exposes this flag via bit[55] of /proc/pid/pagemap,
> and the semantics is not a default one (scheduled to be the default in
> the near future.) However, it shifts to the new semantics at the first
> clear_ref, and the users of soft dirty bit always do it before utilizing
> the bit, so that's not a big deal. Users must avoid relying on the bit
> in page-types before the first clear_ref.
Is Documentation/filesystems/proc.txt (around line 450) fully up to
date here?
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next prev parent reply other threads:[~2013-10-08 0:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-04 19:02 [PATCH 1/2] smaps: show VM_SOFTDIRTY flag in VmFlags line Naoya Horiguchi
2013-10-04 19:02 ` [PATCH 2/2] page-types.c: support KPF_SOFTDIRTY bit Naoya Horiguchi
2013-10-08 0:50 ` Andrew Morton [this message]
2013-10-07 13:21 ` [PATCH 1/2] smaps: show VM_SOFTDIRTY flag in VmFlags line Pavel Emelyanov
2013-10-07 14:15 ` [PATCH 1/2 v2] " Naoya Horiguchi
2013-10-07 21:21 ` Cyrill Gorcunov
2013-10-08 0:51 ` Andrew Morton
2013-10-08 2:54 ` Naoya Horiguchi
2013-10-08 8:59 ` Cyrill Gorcunov
2013-10-08 9:03 ` Cyrill Gorcunov
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