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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F93CEB64DA for ; Wed, 5 Jul 2023 17:31:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232324AbjGERbu (ORCPT ); Wed, 5 Jul 2023 13:31:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231960AbjGERbr (ORCPT ); Wed, 5 Jul 2023 13:31:47 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D33B31BC1 for ; Wed, 5 Jul 2023 10:31:12 -0700 (PDT) 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 8EE516164D for ; Wed, 5 Jul 2023 17:30:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D38CCC433CA; Wed, 5 Jul 2023 17:30:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688578239; bh=5qrbLX+C09gYGu4oixB0May1t4DlUFpi121MwOnwUss=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qtAUkLZW7e0/5FW2eM+0oDqgQ/eRLyVKOHFIFMgjlPQX/tFMcqxFvezb5v0PngP/k CKyZMK7U4mFi18Y1a6zCeAY+c4o54428+yRlBJlG03oO7Pl6XUv9MNtZ9PiMtz8Mu0 9yvtCUY1sntkl8RS0OaMgNI6Bc0pgsjuMPbpMC543zrYJyxRSf0m41y+e9vCZdB7LY eveEIgpo85i97One6Qm+cpHd4FJbVgAPKKH6Dbes9Td17rGihcGk27u2RPQQ6M/0Ik SxO99IORNtS97FLNMbEFAXfj+PHQytz16YEgmGiu2n86cz5eQ2NHlPOzE6Z9XTG3re cTN6pZ/TJHjhA== Date: Wed, 5 Jul 2023 10:30:37 -0700 From: Jaegeuk Kim To: Chao Yu Cc: Daejun Park , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [f2fs-dev] [PATCH v2] f2fs: do not issue small discard commands during checkpoint 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-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <65143701-4c19-ab66-1500-abd1162639cd@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > > 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,