From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9C1CEC0015E for ; Tue, 11 Jul 2023 16:37:51 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-2.v29.lw.sourceforge.com) by sfs-ml-2.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1qJGN4-0002yl-7c; Tue, 11 Jul 2023 16:37:50 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-2.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1qJGMy-0002yZ-30 for linux-f2fs-devel@lists.sourceforge.net; Tue, 11 Jul 2023 16:37:45 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=/lAVWnhVY2YMWP444DXIzJwWbYqB1924lmDJqUSohmM=; b=iBTZ/Fawe/bdeLMT1bAyq2fgoK 8mf7HxcXpa/Nlkwu5E4qW0RqAnhms+iJ4sxhMxSxU95ym8jI2k8NkDIze/dbz0tHyw8jT7nfQxc1R ABFBqnCisSFyyB7eVSkhf2v2QX1mTTnPGu38lizmaW2H4Rbdj+OFUHCg5YB2tluuq+2s=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To :From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=/lAVWnhVY2YMWP444DXIzJwWbYqB1924lmDJqUSohmM=; b=hsbUUxELUJ1ZCBkYP+AT7OCAei K/QYkqHUVxs3FCDqBP+NTsrT0OUQeDyN+N8nFsnHhbjFQi5XP7mR1yPnIc5gxHiYbIgLp7PUBCNlo 5GW1knXgtmD4jL2hvR8lqLkZSKSOeo7/Bv1PQZGEo83zrKqf+vDFnZpgLGds9fVJ7PpE=; Received: from dfw.source.kernel.org ([139.178.84.217]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1qJGMx-004eb0-Ad for linux-f2fs-devel@lists.sourceforge.net; Tue, 11 Jul 2023 16:37:44 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E68ED61565; Tue, 11 Jul 2023 16:37:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C128C433C8; Tue, 11 Jul 2023 16:37:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689093457; bh=xwrQzJ2dPBefw8SrU0veV0e4RUL16gINKdqQOT1r1Os=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=a9bSCGHQml4R4EP5ud3D0GZeI6wk0Hga7xZdCGrwoQrXbNJ+w+vRcBoIA4ahKznoA tEIXn6GB/xAMTeBatsy56IhSDzpWBAJ/vT/JMe4oIxwhYVm9b4U1WwL0V2wI+n5YiE AySCy+WAnNV/Z8JePQgKHYWm4PqLSIGDJFIK1kouLBl77mC4oHpRvdO+zPFMXd40Mk 39U1mVgBytAYct5P2BkBc1c5rj5Qse2gEiKn9oDOrTa7Y1Lh0/NiLvhhYEwi8+bqyG qLTqvLa4g0LdBTel5b7SfrpeZUtuvxDt23wsgaX5lSgRHQVQL+gxhIKLKcFdFllq/Q TELULtaC2yuSg== Date: Tue, 11 Jul 2023 09:37:35 -0700 From: Jaegeuk Kim To: Chao Yu Message-ID: References: <20230613203947.2745943-1-jaegeuk@kernel.org> <50d5fa8c-4fe9-8a03-be78-0b5383e55b62@kernel.org> <65143701-4c19-ab66-1500-abd1162639cd@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Headers-End: 1qJGMx-004eb0-Ad Subject: Re: [f2fs-dev] [PATCH v2] f2fs: do not issue small discard commands during checkpoint X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 07/06, Chao Yu wrote: > On 2023/7/6 1:30, Jaegeuk Kim wrote: > > On 07/04, Chao Yu wrote: > > > On 2023/7/4 18:53, Jaegeuk Kim wrote: > > > > On 07/03, Chao Yu wrote: > > > > > On 2023/6/15 0:10, Jaegeuk Kim wrote: > > > > > > If there're huge # of small discards, this will increase checkpoint latency > > > > > > insanely. Let's issue small discards only by trim. > > > > > > > > > > > > Signed-off-by: Jaegeuk Kim > > > > > > --- > > > > > > > > > > > > Change log from v1: > > > > > > - move the skip logic to avoid dangling objects > > > > > > > > > > > > fs/f2fs/segment.c | 2 +- > > > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > > > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > > > > > index 8c7af8b4fc47..0457d620011f 100644 > > > > > > --- a/fs/f2fs/segment.c > > > > > > +++ b/fs/f2fs/segment.c > > > > > > @@ -2193,7 +2193,7 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi, > > > > > > len = next_pos - cur_pos; > > > > > > if (f2fs_sb_has_blkzoned(sbi) || > > > > > > - (force && len < cpc->trim_minlen)) > > > > > > + !force || len < cpc->trim_minlen) > > > > > > goto skip; > > > > > > > > > > Sorry for late reply. > > > > > > > > > > We have a configuration for such case, what do you think of setting > > > > > max_small_discards to zero? otherwise, w/ above change, max_small_discards > > > > > logic may be broken? > > > > > > > > > > What: /sys/fs/f2fs//max_small_discards > > > > > Date: November 2013 > > > > > Contact: "Jaegeuk Kim" > > > > > Description: Controls the issue rate of discard commands that consist of small > > > > > blocks less than 2MB. The candidates to be discarded are cached until > > > > > checkpoint is triggered, and issued during the checkpoint. > > > > > By default, it is disabled with 0. > > > > > > > > > > Or, if we prefer to disable small_discards by default, what about below change: > > > > > > > > I think small_discards is fine, but need to avoid long checkpoint latency only. > > > > > > I didn't get you, do you mean we can still issue small discard by > > > fstrim, so small_discards functionality is fine? > > > > You got the point. > > Well, actually, what I mean is max_small_discards sysfs entry's functionality > is broken. Now, the entry can not be used to control number of small discards > committed by checkpoint. Could you descrbie this problem first? > > I think there is another way to achieve "avoid long checkpoint latency caused > by committing huge # of small discards", the way is we can set max_small_discards > to small value or zero, w/ such configuration, it will take checkpoint much less > time or no time to committing small discard due to below control logic: > > f2fs_flush_sit_entries() > { > ... > if (!(cpc->reason & CP_DISCARD)) { > cpc->trim_start = segno; > add_discard_addrs(sbi, cpc, false); > } > ... > } > > add_discard_addrs() > { > ... > while (force || SM_I(sbi)->dcc_info->nr_discards <= > SM_I(sbi)->dcc_info->max_discards) { > > It will break the loop once nr_discards is larger than max_discards, if > max_discards is set to zero, checkpoint won't take time to handle small discards. > > ... > if (!de) { > de = f2fs_kmem_cache_alloc(discard_entry_slab, > GFP_F2FS_ZERO, true, NULL); > de->start_blkaddr = START_BLOCK(sbi, cpc->trim_start); > list_add_tail(&de->list, head); > } > ... > } > ... > > Thanks, > > > > > > > > > Thanks, > > > > > > > > > > > > > > > > > From eb89d9b56e817e3046d7fa17165b12416f09d456 Mon Sep 17 00:00:00 2001 > > > > > From: Chao Yu > > > > > Date: Mon, 3 Jul 2023 09:06:53 +0800 > > > > > Subject: [PATCH] Revert "f2fs: enable small discard by default" > > > > > > > > > > This reverts commit d618ebaf0aa83d175658aea5291e0c459d471d39 in order > > > > > to disable small discard by default, so that if there're huge number of > > > > > small discards, it will decrease checkpoint's latency obviously. > > > > > > > > > > Also, this patch reverts 9ac00e7cef10 ("f2fs: do not issue small discard > > > > > commands during checkpoint"), due to it breaks small discard feature which > > > > > may be configured via sysfs entry max_small_discards. > > > > > > > > > > Fixes: 9ac00e7cef10 ("f2fs: do not issue small discard commands during checkpoint") > > > > > Signed-off-by: Chao Yu > > > > > --- > > > > > fs/f2fs/segment.c | 4 ++-- > > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > > > > index 14c822e5c9c9..0a313368f18b 100644 > > > > > --- a/fs/f2fs/segment.c > > > > > +++ b/fs/f2fs/segment.c > > > > > @@ -2193,7 +2193,7 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi, > > > > > len = next_pos - cur_pos; > > > > > > > > > > if (f2fs_sb_has_blkzoned(sbi) || > > > > > - !force || len < cpc->trim_minlen) > > > > > + (force && len < cpc->trim_minlen)) > > > > > goto skip; > > > > > > > > > > f2fs_issue_discard(sbi, entry->start_blkaddr + cur_pos, > > > > > @@ -2269,7 +2269,7 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi) > > > > > atomic_set(&dcc->queued_discard, 0); > > > > > atomic_set(&dcc->discard_cmd_cnt, 0); > > > > > dcc->nr_discards = 0; > > > > > - dcc->max_discards = MAIN_SEGS(sbi) << sbi->log_blocks_per_seg; > > > > > + dcc->max_discards = 0; > > > > > dcc->max_discard_request = DEF_MAX_DISCARD_REQUEST; > > > > > dcc->min_discard_issue_time = DEF_MIN_DISCARD_ISSUE_TIME; > > > > > dcc->mid_discard_issue_time = DEF_MID_DISCARD_ISSUE_TIME; > > > > > -- > > > > > 2.40.1 > > > > > > > > > > > > > > > > > > > > > f2fs_issue_discard(sbi, entry->start_blkaddr + cur_pos, _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel