From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f41.google.com (mail-pa0-f41.google.com [209.85.220.41]) by kanga.kvack.org (Postfix) with ESMTP id 37FA26B0039 for ; Mon, 7 Oct 2013 20:50:20 -0400 (EDT) Received: by mail-pa0-f41.google.com with SMTP id bj1so8110459pad.28 for ; Mon, 07 Oct 2013 17:50:19 -0700 (PDT) Date: Mon, 7 Oct 2013 17:50:16 -0700 From: Andrew Morton Subject: Re: [PATCH 2/2] page-types.c: support KPF_SOFTDIRTY bit Message-Id: <20131007175016.a513865c5ecae4bd5759c2b0@linux-foundation.org> In-Reply-To: <1380913335-17466-2-git-send-email-n-horiguchi@ah.jp.nec.com> References: <1380913335-17466-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1380913335-17466-2-git-send-email-n-horiguchi@ah.jp.nec.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: linux-mm@kvack.org, Wu Fengguang , Pavel Emelyanov , linux-kernel@vger.kernel.org On Fri, 4 Oct 2013 15:02:15 -0400 Naoya Horiguchi 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? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org