From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaegeuk Kim Subject: Re: [PATCH] f2fs: skip checkpoint if having a dirty segment but no prefree at BG_GC -> FG_GC Date: Fri, 24 Feb 2017 10:49:59 -0800 Message-ID: <20170224184959.GD39009@jaegeuk.local> References: <20170224204357.220337-1-guoweichao@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1chKwT-0006vY-So for linux-f2fs-devel@lists.sourceforge.net; Fri, 24 Feb 2017 18:50:09 +0000 Received: from mail.kernel.org ([198.145.29.136]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1chKwR-0003Qt-QC for linux-f2fs-devel@lists.sourceforge.net; Fri, 24 Feb 2017 18:50:09 +0000 Content-Disposition: inline In-Reply-To: <20170224204357.220337-1-guoweichao@huawei.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Weichao Guo Cc: linux-f2fs-devel@lists.sourceforge.net Hi Weichao, On 02/25, Weichao Guo wrote: > When turning to FG_GC from BG_GC, we need to write checkpoint in 2 cases: > * a) BG_GC have made some progress, e.g.: some prefree segments. > * b) There is no victim and no prefree segment. You missed * c) has_not_enough_free_secs() introduced by 6e17bfbc75a5cb ("f2fs: fix to overcome inline_data floods") And, Yunlong pointed that we can't find a case to avoid write_checkpoint() mostly due to c) condition. Thanks, > > For case a), previously, we also check if there is a dirty segment for > infering blocks moving in last BG_GC. But dirty segments do not always > indicate that, BG_GC may just start and do not move any blocks at all. > Futhermore, skipping checkpoint if there are some dirty segments but no > prefree segments is OK. > > Signed-off-by: Weichao Guo > --- > fs/f2fs/gc.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > index 6c996e3..30d206a 100644 > --- a/fs/f2fs/gc.c > +++ b/fs/f2fs/gc.c > @@ -958,7 +958,12 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, bool background) > * enough free sections, we should flush dent/node blocks and do > * garbage collections. > */ > - ret = write_checkpoint(sbi, &cpc); > + if (prefree_segments(sbi)) > + ret = write_checkpoint(sbi, &cpc); > + else if (!__get_victim(sbi, &segno, gc_type) { > + segno = NULL_SEGNO; > + ret = write_checkpoint(sbi, &cpc); > + } > if (ret) > goto stop; > } else if (gc_type == BG_GC && !background) { > -- > 2.10.1 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot