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 9D794C433F5 for ; Fri, 4 Feb 2022 09:11:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354797AbiBDJLA (ORCPT ); Fri, 4 Feb 2022 04:11:00 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:35338 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241375AbiBDJK6 (ORCPT ); Fri, 4 Feb 2022 04:10:58 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2C57A6120E for ; Fri, 4 Feb 2022 09:10:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B216DC004E1; Fri, 4 Feb 2022 09:10:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643965857; bh=V0yE5hxMUdg9LANtbDXwIXfKd8UVrTrz86FSocO9m0M=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=bLr+sVeefq5BQhsVPxD6WVefhoHMwdbI/F4eK9gca8XWfZAxiw2t0V3B6AzTN8vRd cNUbxJXOUtwDoq1hloEFIR9YnO8lcEzgcxDJlcT8KJw11Cs3GvhECM9afPYpQKXPWg zYNMhIVtjsbj8FjbKVffH9bTE7J2BAe+56+/dOptNx8XuoUtKzgEBJevY5NvwMqeUP vSFW2oZzIIaTrwt0u8uALWKV6fqpkhxfdHYb7c3ttao2vN3qUzxKcb0f3zLnllpupd 6D3LVG6BRLDyFOCKXm/D/7EvveUQ7qk42pPj8/Q/bkyS+enVEIjQorbEAobLPrn0St 3+Y944U9TTYbA== Message-ID: <22c3fe49-81aa-e453-8b9c-643f7f590905@kernel.org> Date: Fri, 4 Feb 2022 17:10:53 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case Content-Language: en-US To: Jaegeuk Kim Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net References: <20210928151911.11189-1-chao@kernel.org> <65f6c366-9e5b-fe7f-7c38-061996d1882b@kernel.org> <3e653a3d-ddb9-e115-d871-3659a1ba5530@kernel.org> <96959788-73b2-6e9b-3aa7-b1e23e9da417@kernel.org> From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/12/15 2:56, Jaegeuk Kim wrote: > On 12/12, Chao Yu wrote: >> Ping, >> >> On 2021/10/30 11:02, Chao Yu wrote: >>> On 2021/10/30 1:43, Jaegeuk Kim wrote: >>>> On 10/29, Chao Yu wrote: >>>>> Ping, >>>>> >>>>> On 2021/9/29 8:05, Chao Yu wrote: >>>>>> On 2021/9/29 3:08, Jaegeuk Kim wrote: >>>>>>> On 09/28, Chao Yu wrote: >>>>>>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to >>>>>>>> check whethere it is overwrite case, for such case, we can skip >>>>>>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(), >>>>>>>> which may be blocked by checkpoint() potentially. >>>>>>>> >>>>>>>> Signed-off-by: Chao Yu >>>>>>>> --- >>>>>>>>    fs/f2fs/file.c | 4 ++++ >>>>>>>>    1 file changed, 4 insertions(+) >>>>>>>> >>>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >>>>>>>> index 13deae03df06..51fecb2f4db5 100644 >>>>>>>> --- a/fs/f2fs/file.c >>>>>>>> +++ b/fs/f2fs/file.c >>>>>>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from) >>>>>>>>            preallocated = true; >>>>>>>>            target_size = iocb->ki_pos + iov_iter_count(from); >>>>>>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos, >>>>>>>> +                        iov_iter_count(from))) >>>>>>>> +            goto write; >>>>>>> >>>>>>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte >>>>>>> case. Do we have other benefit? >>>>>> >>>>>> f2fs_overwrite_io() will break for append write case w/ below check: >>>>>> >>>>>>       if (pos + len > i_size_read(inode)) >>>>>>           return false; >>>>>> >>>>>> I guess we may only suffer double f2fs_map_blocks() for write hole >>>>>> case, e.g. truncate to large size & write inside the filesize. For >>>>>> this case, how about adding a condition to allow double f2fs_map_blocks() >>>>>> only if write size is smaller than a threshold? >>>> >>>> I still don't see the benefit much to do double f2fs_map_blocks. What is the >>>> problem here? >>> >>> There is potential hangtask happened during swapfile's writeback: >>> >>> - loop_kthread_worker_fn >>>  - kthread_worker_fn >>>   - loop_queue_work >>>    - lo_rw_aio >>>     - f2fs_file_write_iter >>>      - f2fs_preallocate_blocks >>>       - f2fs_map_blocks >>>        - down_read >>>         - rwsem_down_read_slowpath >>>          - schedule >>> >>> I try to mitigate such issue by preallocating swapfile's block address and >>> avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path... > > How about checking i_blocks and i_size instead of checking the entire map? How about v2? Thanks, > >>> >>> Thanks, >>> >>>> >>>>>> >>>>>> Thanks, >>>>>> >>>>>>> >>>>>>>> + >>>>>>>>            err = f2fs_preallocate_blocks(iocb, from); >>>>>>>>            if (err) { >>>>>>>>    out_err: >>>>>>>> -- >>>>>>>> 2.32.0 >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> Linux-f2fs-devel mailing list >>>>>> Linux-f2fs-devel@lists.sourceforge.net >>>>>> https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&reserved=0 >>> >>> >>> _______________________________________________ >>> Linux-f2fs-devel mailing list >>> Linux-f2fs-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel