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 CC754C4332F for ; Mon, 12 Dec 2022 22:47:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233948AbiLLWrx (ORCPT ); Mon, 12 Dec 2022 17:47:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233961AbiLLWrl (ORCPT ); Mon, 12 Dec 2022 17:47:41 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD82B1C106 for ; Mon, 12 Dec 2022 14:47:17 -0800 (PST) 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 4347A61267 for ; Mon, 12 Dec 2022 22:47:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8897FC433F0; Mon, 12 Dec 2022 22:47:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670885236; bh=4/6SuCNcBrCMb/LiBQ8O3Kf5f2TLbj+uxIKFNs10M08=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dtsJNDNYtTaS7ugd/RUtYb1IRNMuwxpI1uxMVPgWcVH8jzD6VKz/RFks0gYXS9jSr MQKQIOUpwXq5vWFdJgSz6maWW1plOp6YboLgsIHJzpu7BQHnSHVHT8DEqlLBKuGTGz Ae6tCf4nPw2LP82hOvZmUtkOpgGyplUGHy3yioBWkoMBWDUc6KR1HEuY6UylV2BOTk oZp4MWN07gub0vEG/hZle1ALG7/GRY+tItwwh6P9h4WHtG8OmYpYsd0YTNvPqBc1aW lVZKkoMeHGztuD7FBu+P8IgaGoq00UCh4tb8Yg9s94mFBKYiuioBTT0Fj++TJgg6KX SHkSMUklTq0yg== Date: Mon, 12 Dec 2022 14:47:15 -0800 From: Jaegeuk Kim To: Chao Yu Cc: Yangtao Li , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] f2fs: add support for counting time of submit discard cmd Message-ID: References: <20221212125137.77187-1-frank.li@vivo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12, Chao Yu wrote: > On 2022/12/12 20:51, Yangtao Li wrote: > > This patch adds support for counting the average time and > > peak time of submit discard command, and we can see its > > value in debugfs. > > > > It is not sure whether the block layer has recorded these > > data, and these data are allowed to be accessed by fs, > > or they are only exported to user space. > > > > On the one hand, I added these data to better understand > > the current device operating status, and to further control > > the discard process in a more detailed manner based on the > > discard submit time in the future. > > Again, w'd better to consider this functionality only when DEBUG_FS is > enabled. BTW, why can't we use iostat to get the discard latencies? > > > > > Signed-off-by: Yangtao Li > > --- > > fs/f2fs/debug.c | 10 +++++++--- > > fs/f2fs/f2fs.h | 6 ++++++ > > fs/f2fs/segment.c | 21 +++++++++++++++++++-- > > 3 files changed, 32 insertions(+), 5 deletions(-) > > > > diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c > > index 32af4f0c5735..142c256b89d9 100644 > > --- a/fs/f2fs/debug.c > > +++ b/fs/f2fs/debug.c > > @@ -120,6 +120,10 @@ static void update_general_status(struct f2fs_sb_info *sbi) > > llist_empty(&SM_I(sbi)->fcc_info->issue_list); > > } > > if (SM_I(sbi)->dcc_info) { > > + struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info; > > + > > + si->discard_avg = dcc->discard_time_avg; > > + si->discard_peak = dcc->discard_time_peak; > > si->nr_discarded = > > atomic_read(&SM_I(sbi)->dcc_info->issued_discard); > > si->nr_discarding = > > @@ -545,9 +549,9 @@ static int stat_show(struct seq_file *s, void *v) > > si->nr_wb_cp_data, si->nr_wb_data, > > si->nr_flushing, si->nr_flushed, > > si->flush_list_empty); > > - seq_printf(s, "Discard: (%4d %4d)) cmd: %4d undiscard:%4u\n", > > - si->nr_discarding, si->nr_discarded, > > - si->nr_discard_cmd, si->undiscard_blks); > > + seq_printf(s, "Discard: (%4d %4d, avg:%4lldns, peak:%4lldns)) cmd: %4d undiscard:%4u\n", > > + si->nr_discarding, si->nr_discarded, ktime_to_us(si->discard_avg), > > + ktime_to_us(si->discard_peak), si->nr_discard_cmd, si->undiscard_blks); > > seq_printf(s, " - atomic IO: %4d (Max. %4d)\n", > > si->aw_cnt, si->max_aw_cnt); > > seq_printf(s, " - compress: %4d, hit:%8d\n", si->compress_pages, si->compress_page_hit); > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index e8953c3dc81a..2cd55cb981ff 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -371,6 +371,8 @@ struct discard_cmd { > > int error; /* bio error */ > > spinlock_t lock; /* for state/bio_ref updating */ > > unsigned short bio_ref; /* bio reference count */ > > + struct discard_cmd_control *dcc; /* global discard cmd control */ > > + ktime_t submit_start; /* submit start time */ > > }; > > enum { > > @@ -415,6 +417,9 @@ struct discard_cmd_control { > > unsigned int max_ordered_discard; /* maximum discard granularity issued by lba order */ > > unsigned int undiscard_blks; /* # of undiscard blocks */ > > unsigned int next_pos; /* next discard position */ > > + spinlock_t discard_time_lock; /* for discard time statistics */ > > + ktime_t discard_time_avg; /* issued discard cmd avg time */ > > + ktime_t discard_time_peak; /* issued discard cmd peak time */ > > atomic_t issued_discard; /* # of issued discard */ > > atomic_t queued_discard; /* # of queued discard */ > > atomic_t discard_cmd_cnt; /* # of cached cmd count */ > > @@ -3896,6 +3901,7 @@ struct f2fs_stat_info { > > int nr_dio_read, nr_dio_write; > > unsigned int io_skip_bggc, other_skip_bggc; > > int nr_flushing, nr_flushed, flush_list_empty; > > + ktime_t discard_avg, discard_peak; > > int nr_discarding, nr_discarded; > > int nr_discard_cmd; > > unsigned int undiscard_blks; > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > index a9099a754dd2..73cd05bb3f4a 100644 > > --- a/fs/f2fs/segment.c > > +++ b/fs/f2fs/segment.c > > @@ -937,6 +937,7 @@ static struct discard_cmd *__create_discard_cmd(struct f2fs_sb_info *sbi, > > list_add_tail(&dc->list, pend_list); > > spin_lock_init(&dc->lock); > > dc->bio_ref = 0; > > + dc->dcc = dcc; > > atomic_inc(&dcc->discard_cmd_cnt); > > dcc->undiscard_blks += len; > > @@ -1006,9 +1007,13 @@ static void __remove_discard_cmd(struct f2fs_sb_info *sbi, > > static void f2fs_submit_discard_endio(struct bio *bio) > > { > > struct discard_cmd *dc = (struct discard_cmd *)bio->bi_private; > > + struct discard_cmd_control *dcc = dc->dcc; > > unsigned long flags; > > + ktime_t submit_time; > > + int nr_discarded; > > spin_lock_irqsave(&dc->lock, flags); > > + submit_time = ktime_sub(ktime_get(), dc->submit_start); > > if (!dc->error) > > dc->error = blk_status_to_errno(bio->bi_status); > > dc->bio_ref--; > > @@ -1018,6 +1023,16 @@ static void f2fs_submit_discard_endio(struct bio *bio) > > } > > spin_unlock_irqrestore(&dc->lock, flags); > > bio_put(bio); > > + > > + spin_lock_irqsave(&dcc->discard_time_lock, flags); > > + nr_discarded = atomic_read(&dcc->issued_discard); > > + dcc->discard_time_avg = div_u64(ktime_add(nr_discarded * dcc->discard_time_avg, > > + submit_time), > > + nr_discarded + 1); > > + if (dcc->discard_time_avg > dcc->discard_time_peak) > > + dcc->discard_time_peak = dcc->discard_time_avg; > > + atomic_inc(&dcc->issued_discard); > > + spin_unlock_irqrestore(&dcc->discard_time_lock, flags); > > Why not calculating average time only in update_general_status()? and here, > we just need to account total_{discard_time, discard_count} w/o additional > spinlock. > > Thanks, > > > } > > static void __check_sit_bitmap(struct f2fs_sb_info *sbi, > > @@ -1166,6 +1181,7 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi, > > * right away > > */ > > spin_lock_irqsave(&dc->lock, flags); > > + dc->submit_start = ktime_get(); > > if (last) > > dc->state = D_SUBMIT; > > else > > @@ -1185,8 +1201,6 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi, > > bio->bi_opf |= flag; > > submit_bio(bio); > > - atomic_inc(&dcc->issued_discard); > > - > > f2fs_update_iostat(sbi, NULL, FS_DISCARD, len * F2FS_BLKSIZE); > > lstart += len; > > @@ -2079,9 +2093,12 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi) > > INIT_LIST_HEAD(&dcc->wait_list); > > INIT_LIST_HEAD(&dcc->fstrim_list); > > mutex_init(&dcc->cmd_lock); > > + spin_lock_init(&dcc->discard_time_lock); > > atomic_set(&dcc->issued_discard, 0); > > atomic_set(&dcc->queued_discard, 0); > > atomic_set(&dcc->discard_cmd_cnt, 0); > > + dcc->discard_time_avg = 0; > > + dcc->discard_time_peak = 0; > > dcc->nr_discards = 0; > > dcc->max_discards = MAIN_SEGS(sbi) << sbi->log_blocks_per_seg; > > dcc->max_discard_request = DEF_MAX_DISCARD_REQUEST;