Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754781AbaKSNL5 (ORCPT ); Wed, 19 Nov 2014 08:11:57 -0500 Received: from mta-out1.inet.fi ([62.71.2.203]:44844 "EHLO kirsi1.inet.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752741AbaKSNL4 (ORCPT ); Wed, 19 Nov 2014 08:11:56 -0500 Date: Wed, 19 Nov 2014 15:11:37 +0200 From: "Kirill A. Shutemov" To: Naoya Horiguchi Cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Dave Hansen , Hugh Dickins , Mel Gorman , Rik van Riel , Vlastimil Babka , Christoph Lameter , Steve Capper , "Aneesh Kumar K.V" , Johannes Weiner , Michal Hocko , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH 16/19] thp: update documentation Message-ID: <20141119131137.GD29884@node.dhcp.inet.fi> References: <1415198994-15252-1-git-send-email-kirill.shutemov@linux.intel.com> <1415198994-15252-17-git-send-email-kirill.shutemov@linux.intel.com> <20141119080828.GA11447@hori1.linux.bs1.fc.nec.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141119080828.GA11447@hori1.linux.bs1.fc.nec.co.jp> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 19, 2014 at 08:07:59AM +0000, Naoya Horiguchi wrote: > On Wed, Nov 05, 2014 at 04:49:51PM +0200, Kirill A. Shutemov wrote: > > The patch updates Documentation/vm/transhuge.txt to reflect changes in > > THP design. > > > > Signed-off-by: Kirill A. Shutemov > > --- > > Documentation/vm/transhuge.txt | 84 +++++++++++++++++++----------------------- > > 1 file changed, 38 insertions(+), 46 deletions(-) > > > > diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt > > index df1794a9071f..33465e7b0d9b 100644 > > --- a/Documentation/vm/transhuge.txt > > +++ b/Documentation/vm/transhuge.txt > > @@ -200,9 +200,18 @@ thp_collapse_alloc_failed is incremented if khugepaged found a range > > of pages that should be collapsed into one huge page but failed > > the allocation. > > > > -thp_split is incremented every time a huge page is split into base > > +thp_split_page is incremented every time a huge page is split into base > > pages. This can happen for a variety of reasons but a common > > reason is that a huge page is old and is being reclaimed. > > + This action implies splitting all PMD the page mapped with. > > + > > +thp_split_page_failed is is incremented if kernel fails to split huge > > 'is' appears twice. > > > + page. This can happen if the page was pinned by somebody. > > + > > +thp_split_pmd is incremented every time a PMD split into table of PTEs. > > + This can happen, for instance, when application calls mprotect() or > > + munmap() on part of huge page. It doesn't split huge page, only > > + page table entry. > > > > thp_zero_page_alloc is incremented every time a huge zero page is > > successfully allocated. It includes allocations which where > > There is a sentense related to the adjustment on futex code you just > removed in patch 15/19 in "get_user_pages and follow_page" section. > > ... > split_huge_page() to avoid the head and tail pages to disappear from > under it, see the futex code to see an example of that, hugetlbfs also > needed special handling in futex code for similar reasons). > > this seems obsolete, so we need some change on this? I'll update documentation futher once patchset will be closer to ready state. -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/