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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 CB160C433DF for ; Tue, 4 Aug 2020 01:04:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF1002075A for ; Tue, 4 Aug 2020 01:04:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596503054; bh=qmi+JueUhqtxSSAhKDVOtsYflLhRFP7QuN1kV0mi6Ww=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=xoMJf3jF/AxmDa/VckuC5iNeO1GG1DkMt0soIKm11PDHoH+tCx2DMyefE9503+JJG rEiS27lE8XaF6oi41bHG2zI/NR6aFdEboG9j+Yonw2jt2B0xiBd52KgK0pSYOO+DDd rgbIoBC1xNVigyuf0KVvGW9OoyhUKexZDfP9NpVA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728015AbgHDBEN (ORCPT ); Mon, 3 Aug 2020 21:04:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:36816 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726276AbgHDBEN (ORCPT ); Mon, 3 Aug 2020 21:04:13 -0400 Received: from localhost (unknown [104.132.1.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DC6E92073E; Tue, 4 Aug 2020 01:04:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596503053; bh=qmi+JueUhqtxSSAhKDVOtsYflLhRFP7QuN1kV0mi6Ww=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JCDMcA5cmLaDlupv89ziUjEvTG1gl57Pbq1UH2tlRjSLVitp46r+u11Xj6MKW8Bd/ xvhIzBdKHmgKjKtxJI93gFcLD6d9GhZj6/a+wA/IxnW4dkrgAQAiv/Z5Bz4WxBk9iW z3wh9AAAyxQArz/3ppjXAEOWu9URYtyLM0Ywly3M= Date: Mon, 3 Aug 2020 18:04:12 -0700 From: Jaegeuk Kim To: Chao Yu Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com, Eric Biggers Subject: Re: [f2fs-dev] [PATCH] f2fs: remove a waiter for checkpoint completion Message-ID: <20200804010412.GA866340@google.com> References: <20200803172825.4077289-1-jaegeuk@kernel.org> <9638d2c5-cfd0-359f-187a-8e23bc6d822d@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9638d2c5-cfd0-359f-187a-8e23bc6d822d@huawei.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/04, Chao Yu wrote: > On 2020/8/4 1:28, Jaegeuk Kim wrote: > > It doesn't need to wait for checkpoint being completed triggered by end_io. > > > > [ 20.157753] ------------[ cut here ]------------ > > [ 20.158393] do not call blocking ops when !TASK_RUNNING; state=2 set at [<0000000096354225>] prepare_to_wait+0xcd/0x430 > > [ 20.159858] WARNING: CPU: 1 PID: 1152 at kernel/sched/core.c:7142 __might_sleep+0x149/0x1a0 > > ... > > [ 20.176110] __submit_merged_write_cond+0x191/0x310 > > [ 20.176739] f2fs_submit_merged_write+0x18/0x20 > > [ 20.177323] f2fs_wait_on_all_pages+0x269/0x2d0 > > [ 20.177899] ? block_operations+0x980/0x980 > > [ 20.178441] ? __kasan_check_read+0x11/0x20 > > [ 20.178975] ? finish_wait+0x260/0x260 > > [ 20.179488] ? percpu_counter_set+0x147/0x230 > > [ 20.180049] do_checkpoint+0x1757/0x2a50 > > [ 20.180558] f2fs_write_checkpoint+0x840/0xaf0 > > [ 20.181126] f2fs_sync_fs+0x287/0x4a0 > > > > Reported-by: Eric Biggers > > Signed-off-by: Jaegeuk Kim > > --- > > fs/f2fs/checkpoint.c | 6 +----- > > fs/f2fs/data.c | 4 ---- > > fs/f2fs/f2fs.h | 1 - > > fs/f2fs/super.c | 1 - > > 4 files changed, 1 insertion(+), 11 deletions(-) > > > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > > index 99c8061da55b9..2bdddc725e677 100644 > > --- a/fs/f2fs/checkpoint.c > > +++ b/fs/f2fs/checkpoint.c > > @@ -1255,11 +1255,7 @@ static void unblock_operations(struct f2fs_sb_info *sbi) > > void f2fs_wait_on_all_pages(struct f2fs_sb_info *sbi, int type) > > { > > - DEFINE_WAIT(wait); > > - > > for (;;) { > > - prepare_to_wait(&sbi->cp_wait, &wait, TASK_UNINTERRUPTIBLE); > > Wouldn't that case high cpu usage before io end? This is a critical path to wait for IO completion in checkpoint, which would be better to wait for it to avoid long latency to continue filesystem operations. Moreover, I expect io_schedule_timeout() can mitigate such the CPU overhead and actually we don't need to make there-in context switches as well. > > > - > > if (!get_pages(sbi, type)) > > break; > > @@ -1271,9 +1267,9 @@ void f2fs_wait_on_all_pages(struct f2fs_sb_info *sbi, int type) > > FS_CP_META_IO); > > else if (type == F2FS_WB_CP_DATA) > > f2fs_submit_merged_write(sbi, DATA); > > + > > io_schedule_timeout(DEFAULT_IO_TIMEOUT); > > } > > - finish_wait(&sbi->cp_wait, &wait); > > } > > static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc) > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index c1b676be67b9a..588d2871bbe69 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -383,10 +383,6 @@ static void f2fs_write_end_io(struct bio *bio) > > clear_cold_data(page); > > end_page_writeback(page); > > } > > - if (!get_pages(sbi, F2FS_WB_CP_DATA) && > > - wq_has_sleeper(&sbi->cp_wait)) > > - wake_up(&sbi->cp_wait); > > - > > bio_put(bio); > > } > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index 02811ce15059b..a036539363030 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -1437,7 +1437,6 @@ struct f2fs_sb_info { > > struct rw_semaphore cp_rwsem; /* blocking FS operations */ > > struct rw_semaphore node_write; /* locking node writes */ > > struct rw_semaphore node_change; /* locking node change */ > > - wait_queue_head_t cp_wait; > > unsigned long last_time[MAX_TIME]; /* to store time in jiffies */ > > long interval_time[MAX_TIME]; /* to store thresholds */ > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > > index 83bf9a02f83f2..5f4d9abc079d6 100644 > > --- a/fs/f2fs/super.c > > +++ b/fs/f2fs/super.c > > @@ -3540,7 +3540,6 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) > > init_rwsem(&sbi->cp_rwsem); > > init_rwsem(&sbi->quota_sem); > > - init_waitqueue_head(&sbi->cp_wait); > > init_sb_info(sbi); > > err = init_percpu_info(sbi); > >