linux-kernel - Re: [PATCHv6 01/36] mm, proc: adjust PSS calculation

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Date:	Mon, 22 Jun 2015 13:02:45 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Dave Hansen <dave.hansen@...el.com>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
	Christoph Lameter <cl@...two.org>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Steve Capper <steve.capper@...aro.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>,
	Jerome Marchand <jmarchan@...hat.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv6 01/36] mm, proc: adjust PSS calculation

On Tue, Jun 09, 2015 at 02:29:17PM +0200, Vlastimil Babka wrote:
> On 06/03/2015 07:05 PM, Kirill A. Shutemov wrote:
> >With new refcounting all subpages of the compound page are not nessessary
> >have the same mapcount. We need to take into account mapcount of every
> >sub-page.
> >
> >Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> >Tested-by: Sasha Levin <sasha.levin@...cle.com>
> >Acked-by: Jerome Marchand <jmarchan@...hat.com>
> >Acked-by: Vlastimil Babka <vbabka@...e.cz>
> >---
> >  fs/proc/task_mmu.c | 48 +++++++++++++++++++++++++++++++-----------------
> >  1 file changed, 31 insertions(+), 17 deletions(-)
> >
> >diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> >index 58be92e11939..f9b285761bc0 100644
> >--- a/fs/proc/task_mmu.c
> >+++ b/fs/proc/task_mmu.c
> >@@ -449,9 +449,10 @@ struct mem_size_stats {
> >  };
> >
> >  static void smaps_account(struct mem_size_stats *mss, struct page *page,
> >-		unsigned long size, bool young, bool dirty)
> >+		bool compound, bool young, bool dirty)
> >  {
> >-	int mapcount;
> >+	int i, nr = compound ? HPAGE_PMD_NR : 1;
> >+	unsigned long size = nr * PAGE_SIZE;
> >
> >  	if (PageAnon(page))
> >  		mss->anonymous += size;
> >@@ -460,23 +461,36 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page,
> >  	/* Accumulate the size in pages that have been accessed. */
> >  	if (young || PageReferenced(page))
> >  		mss->referenced += size;
> >-	mapcount = page_mapcount(page);
> >-	if (mapcount >= 2) {
> >-		u64 pss_delta;
> >
> >-		if (dirty || PageDirty(page))
> >-			mss->shared_dirty += size;
> >-		else
> >-			mss->shared_clean += size;
> >-		pss_delta = (u64)size << PSS_SHIFT;
> >-		do_div(pss_delta, mapcount);
> >-		mss->pss += pss_delta;
> >-	} else {
> >+	/*
> >+	 * page_count(page) == 1 guarantees the page is mapped exactly once.
> >+	 * If any subpage of the compound page mapped with PTE it would elevate
> >+	 * page_count().
> >+	 */
> >+	if (page_count(page) == 1) {
> >  		if (dirty || PageDirty(page))
> >  			mss->private_dirty += size;
> >  		else
> >  			mss->private_clean += size;
> >-		mss->pss += (u64)size << PSS_SHIFT;
> 
> Deleting the line above was a mistake, right?

Yep :-/

-- 
 Kirill A. Shutemov
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