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=0.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH, UNWANTED_LANGUAGE_BODY,URIBL_BLOCKED,USER_AGENT_MUTT 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 D8BA2C3279B for ; Fri, 6 Jul 2018 22:45:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7571022B26 for ; Fri, 6 Jul 2018 22:45:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="X+d90xCP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7571022B26 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932774AbeGFWpf (ORCPT ); Fri, 6 Jul 2018 18:45:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:33894 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754151AbeGFWpe (ORCPT ); Fri, 6 Jul 2018 18:45:34 -0400 Received: from localhost (unknown [104.132.1.88]) (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 E82762254A; Fri, 6 Jul 2018 22:45:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1530917134; bh=m1AHk0kxn8cU6eoYLpljWt81Wyc9fqlz4RpKYugmF2o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=X+d90xCPiF+zqVDlHegibjwHqjKpGgBuCkRDZXkPGBsEuB1Ya128nNWigOfoShEjz 0uB52UbnB7klPjbX9lS/5GhjXsjahYKKlKOJruFOt2WPrsRAr1O7ACBQhS2C7Ob0f2 Rbss21pLDAKme38mrKHQygB2bphSTOw0PX0ZZ3x4= Date: Fri, 6 Jul 2018 15:45:33 -0700 From: Jaegeuk Kim To: Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu Subject: Re: [PATCH] f2fs: split discard command in prior to block layer Message-ID: <20180706224533.GC77984@jaegeuk-macbookpro.roam.corp.google.com> References: <20180704153746.2510-1-chao@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180704153746.2510-1-chao@kernel.org> User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/04, Chao Yu wrote: > From: Chao Yu > > Some devices has small max_{hw,}discard_sectors, so that in > __blkdev_issue_discard(), one big size discard bio can be split > into multiple small size discard bios, result in heavy load in IO > scheduler and device, which can hang other sync IO for long time. > > Now, f2fs is trying to control discard commands more elaboratively, > in order to make less conflict in between discard IO and user IO > to enhance application's performance, so in this patch, we will > split discard bio in f2fs in prior to in block layer to reduce > issuing multiple discard bios in a short time. Hi Chao, In terms of # of candidates, can we control this when actually issuing the discard commands? Thanks, > > Signed-off-by: Chao Yu > --- > fs/f2fs/f2fs.h | 13 ++++++------- > fs/f2fs/segment.c | 25 ++++++++++++++++++++++--- > 2 files changed, 28 insertions(+), 10 deletions(-) > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index a9da5a089cb4..a09d2b2d9520 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -178,7 +178,6 @@ enum { > > #define MAX_DISCARD_BLOCKS(sbi) BLKS_PER_SEC(sbi) > #define DEF_MAX_DISCARD_REQUEST 8 /* issue 8 discards per round */ > -#define DEF_MAX_DISCARD_LEN 512 /* Max. 2MB per discard */ > #define DEF_MIN_DISCARD_ISSUE_TIME 50 /* 50 ms, if exists */ > #define DEF_MID_DISCARD_ISSUE_TIME 500 /* 500 ms, if device busy */ > #define DEF_MAX_DISCARD_ISSUE_TIME 60000 /* 60 s, if no candidates */ > @@ -701,22 +700,22 @@ static inline void set_extent_info(struct extent_info *ei, unsigned int fofs, > } > > static inline bool __is_discard_mergeable(struct discard_info *back, > - struct discard_info *front) > + struct discard_info *front, unsigned int max_len) > { > return (back->lstart + back->len == front->lstart) && > - (back->len + front->len < DEF_MAX_DISCARD_LEN); > + (back->len + front->len <= max_len); > } > > static inline bool __is_discard_back_mergeable(struct discard_info *cur, > - struct discard_info *back) > + struct discard_info *back, unsigned int max_len) > { > - return __is_discard_mergeable(back, cur); > + return __is_discard_mergeable(back, cur, max_len); > } > > static inline bool __is_discard_front_mergeable(struct discard_info *cur, > - struct discard_info *front) > + struct discard_info *front, unsigned int max_len) > { > - return __is_discard_mergeable(cur, front); > + return __is_discard_mergeable(cur, front, max_len); > } > > static inline bool __is_extent_mergeable(struct extent_info *back, > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 4648561e2bfd..8e417a12684d 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -1086,6 +1086,9 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > struct discard_cmd *dc; > struct discard_info di = {0}; > struct rb_node **insert_p = NULL, *insert_parent = NULL; > + struct request_queue *q = bdev_get_queue(bdev); > + unsigned int max_discard_blocks = > + SECTOR_TO_BLOCK(q->limits.max_discard_sectors); > block_t end = lstart + len; > > mutex_lock(&dcc->cmd_lock); > @@ -1129,7 +1132,8 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > > if (prev_dc && prev_dc->state == D_PREP && > prev_dc->bdev == bdev && > - __is_discard_back_mergeable(&di, &prev_dc->di)) { > + __is_discard_back_mergeable(&di, &prev_dc->di, > + max_discard_blocks)) { > prev_dc->di.len += di.len; > dcc->undiscard_blks += di.len; > __relocate_discard_cmd(dcc, prev_dc); > @@ -1140,7 +1144,8 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > > if (next_dc && next_dc->state == D_PREP && > next_dc->bdev == bdev && > - __is_discard_front_mergeable(&di, &next_dc->di)) { > + __is_discard_front_mergeable(&di, &next_dc->di, > + max_discard_blocks)) { > next_dc->di.lstart = di.lstart; > next_dc->di.len += di.len; > next_dc->di.start = di.start; > @@ -1170,7 +1175,11 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > static int __queue_discard_cmd(struct f2fs_sb_info *sbi, > struct block_device *bdev, block_t blkstart, block_t blklen) > { > + struct request_queue *q = bdev_get_queue(bdev); > + unsigned int max_discard_blocks = > + SECTOR_TO_BLOCK(q->limits.max_discard_sectors); > block_t lblkstart = blkstart; > + block_t total_len = blklen; > > trace_f2fs_queue_discard(bdev, blkstart, blklen); > > @@ -1179,7 +1188,17 @@ static int __queue_discard_cmd(struct f2fs_sb_info *sbi, > > blkstart -= FDEV(devi).start_blk; > } > - __update_discard_tree_range(sbi, bdev, lblkstart, blkstart, blklen); > + > + while (total_len) { > + if (blklen > max_discard_blocks) > + blklen = max_discard_blocks; > + __update_discard_tree_range(sbi, bdev, lblkstart, > + blkstart, blklen); > + lblkstart += blklen; > + blkstart += blklen; > + total_len -= blklen; > + blklen = total_len; > + } > return 0; > } > > -- > 2.16.2.17.g38e79b1fd