Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752408AbaGHEtf (ORCPT ); Tue, 8 Jul 2014 00:49:35 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:57911 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750927AbaGHEtd (ORCPT ); Tue, 8 Jul 2014 00:49:33 -0400 Date: Mon, 7 Jul 2014 21:48:46 -0700 From: Andrew Morton To: Gioh Kim Cc: Laura Abbott , Michal Nazarewicz , Marek Szyprowski , Joonsoo Kim , Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?Q?=EC=9D=B4=EA=B1=B4=ED=98=B8?= , Gi-Oh Kim Subject: Re: [PATCH] [RFC] CMA: clear buffer-head lru before page migration Message-Id: <20140707214846.0224d697.akpm@linux-foundation.org> In-Reply-To: <53BB7714.2020102@lge.com> References: <53B664E5.5060102@lge.com> <20140707155252.15e81dff6683393ba3590478@linux-foundation.org> <53BB7714.2020102@lge.com> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 08 Jul 2014 13:44:04 +0900 Gioh Kim wrote: > 2014-07-08 ______ 7:52, Andrew Morton ___ ___: > > On Fri, 04 Jul 2014 17:25:09 +0900 Gioh Kim wrote: > > > >> From: Gioh Kim > >> Date: Fri, 4 Jul 2014 16:53:22 +0900 > >> Subject: [PATCH] [RFC] CMA: clear buffer-head lru before page migration > >> > >> When CMA try to migrate page, some buffer-heads can exist on lru. > >> The bh on lru has non-zero count value so that it cannot be dropped > >> even-if it is not used. We can drop only buffers related to the > >> migrated page, but it can take long time more than dropping all > >> because of searching list. There all buffers in lru are dropped. > >> > >> Signed-off-by: Laura Abbott > >> Signed-off-by: Gioh Kim > >> --- > >> fs/buffer.c | 13 +++++++++++++ > >> 1 file changed, 13 insertions(+) > >> > >> diff --git a/fs/buffer.c b/fs/buffer.c > >> index eba6e4f..4f11b7a 100644 > >> --- a/fs/buffer.c > >> +++ b/fs/buffer.c > >> @@ -3233,6 +3233,19 @@ int try_to_free_buffers(struct page *page) > >> if (PageWriteback(page)) > >> return 0; > >> > >> +#ifdef CONFIG_CMA > >> + /* > >> + * When CMA try to migrate page, some buffer-heads can exist on lru. > >> + * The bh on lru has non-zero count value so that it cannot > >> + * be dropped even-if it is not used. > >> + * We can drop only buffers related to the migrated page, > >> + * but it can take long time more than dropping all > >> + * because of searching list. > >> + * There all buffers in lru are dropped first. > >> + */ > >> + invalidate_bh_lrus(); > >> +#endif > > > > No, this will be tremendously expensive. > > > > What I proposed is that CMA call invalidate_bh_lrus() right at the > > outset. Something along the lines of Please do not top-post your email replies - it makes it very hard to conduct a coherent discussion. > It's my fault. > I'm going to send another patch ASAP. No, not "ASAP". Such a patch will require careful testing on numerous system configurations and workloads. Take however much time it needs to get it right. -- 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/