From: Eric Sandeen Subject: Re: [PATCH] Set the initial TRIM information as TRIMMED Date: Thu, 01 Dec 2011 16:06:57 -0600 Message-ID: <4ED7FA81.9090802@redhat.com> References: <20111201070052.GA29708@july> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: tytso@mit.edu, tm@tao.ma, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: Kyungmin Park Return-path: Received: from mx1.redhat.com ([209.132.183.28]:20246 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754543Ab1LAWHJ (ORCPT ); Thu, 1 Dec 2011 17:07:09 -0500 In-Reply-To: <20111201070052.GA29708@july> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 12/1/11 1:00 AM, Kyungmin Park wrote: > From: Kyungmin Park > > Now trim information doesn't stored at disk so every boot time. it's cleared. > and do the trim all disk groups. > But assume that it's already trimmed at previous time so don't need to trim it again. So set the intial state as trimmed. > > Signed-off-by: Kyungmin Park > --- > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > index e2d8be8..97ef342 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -1098,6 +1098,12 @@ int ext4_mb_init_group(struct super_block *sb, ext4_group_t group) > goto err; > } > mark_page_accessed(page); > + > + /* > + * TRIM information is not stored at disk so set the initial > + * state as trimmed. Since previous time it's already trimmed all > + */ > + EXT4_MB_GRP_SET_TRIMMED(this_grp); Hm, so if there were freed but un-trimmed blocks at this point, we will never trim them until we free _another_ block in the group, right? That might be a reasonable tradeoff, but it is somewhat surprising behavior. i.e. say we do: mount /mnt rm -rf /mnt/very_big_file umount /mnt mount /mnt fitrim /mnt then we won't trim anything at all, right, despite there being many new free blocks? Which would be rather unexpected. If we don't store the trimmed state on disk, I think we should probably stick with the slower first-time trim, and the more obvious behavior (all free blocks are always trimmed whenever a trim command is issued). -Eric > err: > ext4_mb_put_buddy_page_lock(&e4b); > return ret; > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html