From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755503AbdKJAXg (ORCPT ); Thu, 9 Nov 2017 19:23:36 -0500 Received: from LGEAMRELO11.lge.com ([156.147.23.51]:40887 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755252AbdKJAXe (ORCPT ); Thu, 9 Nov 2017 19:23:34 -0500 X-Original-SENDERIP: 156.147.1.121 X-Original-MAILFROM: hyc.lee@gmail.com X-Original-SENDERIP: 10.177.225.35 X-Original-MAILFROM: hyc.lee@gmail.com Message-ID: <5A04F184.3000204@gmail.com> Date: Fri, 10 Nov 2017 09:23:32 +0900 From: Hyunchul Lee User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Chao Yu CC: Jaegeuk Kim , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, kernel-team@lge.com, Hyunchul Lee Subject: Re: [RFC PATCH 0/2] apply write hints to select the type of segments References: <1510206688-12767-1-git-send-email-hyc.lee@gmail.com> <1b0b44de-c724-5dc4-e9cb-79a894bdb611@huawei.com> In-Reply-To: <1b0b44de-c724-5dc4-e9cb-79a894bdb611@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Chao On 11/09/2017 06:12 PM, Chao Yu wrote: > On 2017/11/9 13:51, Hyunchul Lee wrote: >> From: Hyunchul Lee >> >> Using write hints[1], applications can inform the life time of the data >> written to devices. and this[2] reported that the write hints patch >> decreased writes in NAND by 25%. >> >> This hints help F2FS to determine the followings. >> 1) the segment types where the data will be written. >> 2) the hints that will be passed down to devices with the data of segments. >> >> This patch set implements the first mapping from write hints to segment types >> as shown below. >> >> hints segment type >> ----- ------------ >> WRITE_LIFE_SHORT CURSEG_COLD_DATA >> WRITE_LIFE_EXTREME CURSEG_HOT_DATA >> others CURSEG_WARM_DATA >> >> The F2FS poliy for hot/cold seperation has precedence over this hints, And >> hints are not applied in in-place update. > > Could we change to disable IPU if file/inode write hint is existing? > I am afraid that this makes side effects. for example, this could cause out-of-place updates even when there are not enough free segments. I can write the patch that handles these situations. But I wonder that this is required, and I am not sure which IPU polices can be disabled. >> >> Before the second mapping is implemented, write hints are not passed down >> to devices. Because it is better that the data of a segment have the same >> hint. >> >> [1]: c75b1d9421f80f4143e389d2d50ddfc8a28c8c35 >> [2]: https://lwn.net/Articles/726477/ > > Could you write a patch to support passing write hint to block layer for > buffered writes as below commit: > 0127251c45ae ("ext4: add support for passing in write hints for buffered writes") > Sure I will. I wrote it already ;) I think that datas from the same segment should be passed down with the same hint, and the following mapping is reasonable. I wonder what is your opinion about it. segment type hints ------------ ----- CURSEG_COLD_DATA WRITE_LIFE_EXTREME CURSEG_HOT_DATA WRITE_LIFE_SHORT CURSEG_COLD_NODE WRITE_LIFE_NORMAL CURSEG_HOT_NODE WRITE_LIFE_MEDIUM others WRITE_LIFE_NONE > Thanks, > >> >> Hyunchul Lee (2): >> f2fs: apply write hints to select the type of segments for buffered >> write >> f2fs: apply write hints to select the type of segment for direct write >> >> fs/f2fs/data.c | 101 ++++++++++++++++++++++++++++++++---------------------- >> fs/f2fs/f2fs.h | 1 + >> fs/f2fs/segment.c | 14 +++++++- >> 3 files changed, 74 insertions(+), 42 deletions(-) >> > > Thanks