From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752218Ab1KEOiW (ORCPT ); Sat, 5 Nov 2011 10:38:22 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:48105 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751734Ab1KEOiV (ORCPT ); Sat, 5 Nov 2011 10:38:21 -0400 Message-ID: <1320503897.2428.8.camel@discretia> Subject: [PATCH] mm: migrate: One less atomic operation From: Jacobo Giralt To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, mgorman@suse.de, minchan.kim@gmail.com, hughd@google.com, hannes@cmpxchg.org, npiggin@suse.de Date: Sat, 05 Nov 2011 15:38:17 +0100 Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.0- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>From 3754c8617ef4377ce2ca2e3b28bdc28f8de1aa0d Mon Sep 17 00:00:00 2001 From: Jacobo Giralt Date: Sat, 5 Nov 2011 13:12:50 +0100 Subject: [PATCH] mm: migrate: One less atomic operation migrate_page_move_mapping drops a reference from the old page after unfreezing its counter. Both operations can be merged into a single atomic operation by directly unfreezing to one less reference. The same applies to migrate_huge_page_move_mapping. Signed-off-by: Jacobo Giralt --- mm/migrate.c | 10 ++++------ 1 files changed, 4 insertions(+), 6 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 33358f8..46d04a0 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -269,12 +269,12 @@ static int migrate_page_move_mapping(struct address_space *mapping, radix_tree_replace_slot(pslot, newpage); - page_unfreeze_refs(page, expected_count); /* - * Drop cache reference from old page. + * Drop cache reference from old page by unfreezing + * to one less reference. * We know this isn't the last reference. */ - __put_page(page); + page_unfreeze_refs(page, expected_count - 1); /* * If moved to a different zone then also account @@ -334,9 +334,7 @@ int migrate_huge_page_move_mapping(struct address_space *mapping, radix_tree_replace_slot(pslot, newpage); - page_unfreeze_refs(page, expected_count); - - __put_page(page); + page_unfreeze_refs(page, expected_count - 1); spin_unlock_irq(&mapping->tree_lock); return 0; -- 1.7.5.4