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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28F0CC34031 for ; Wed, 19 Feb 2020 03:01:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE03A22B48 for ; Wed, 19 Feb 2020 03:01:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728300AbgBSDB2 (ORCPT ); Tue, 18 Feb 2020 22:01:28 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:36894 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728187AbgBSDB2 (ORCPT ); Tue, 18 Feb 2020 22:01:28 -0500 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 580147073D7EF8328B36; Wed, 19 Feb 2020 11:01:23 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.213) with Microsoft SMTP Server (TLS) id 14.3.439.0; Wed, 19 Feb 2020 11:01:21 +0800 Subject: Re: [f2fs-dev] [PATCH 3/3] f2fs: skip migration only when BG_GC is called To: Jaegeuk Kim CC: , References: <20200214185855.217360-1-jaegeuk@kernel.org> <20200214185855.217360-3-jaegeuk@kernel.org> <9c497f3e-3399-e4a6-f81c-6c4a1f35e5bb@huawei.com> <20200218232714.GB10213@google.com> From: Chao Yu Message-ID: <117a927f-7128-b5a1-a961-22934bb62ec5@huawei.com> Date: Wed, 19 Feb 2020 11:01:21 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200218232714.GB10213@google.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/2/19 7:27, Jaegeuk Kim wrote: > On 02/17, Chao Yu wrote: >> On 2020/2/15 2:58, Jaegeuk Kim wrote: >>> FG_GC needs to move entire section more quickly. >>> >>> Signed-off-by: Jaegeuk Kim >>> --- >>> fs/f2fs/gc.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>> index bbf4db3f6bb4..1676eebc8c8b 100644 >>> --- a/fs/f2fs/gc.c >>> +++ b/fs/f2fs/gc.c >>> @@ -1203,7 +1203,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi, >>> >>> if (get_valid_blocks(sbi, segno, false) == 0) >>> goto freed; >>> - if (__is_large_section(sbi) && >>> + if (gc_type == BG_GC && __is_large_section(sbi) && >>> migrated >= sbi->migration_granularity) >> >> I knew migrating one large section is a more efficient way, but this can >> increase long-tail latency of f2fs_balance_fs() occasionally, especially in >> extreme fragmented space. > > FG_GC requires to wait for whole section migration which shows the entire > latency. That will cause long-tail latency for single f2fs_balance_fs() procedure, which it looks a very long hang when userspace call f2fs syscall, so why not splitting total elapsed time into several f2fs_balance_fs() to avoid that. Thanks, > >> >> Thanks, >> >>> goto skip; >>> if (!PageUptodate(sum_page) || unlikely(f2fs_cp_error(sbi))) >>> > . >