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 AAA96C4332F for ; Tue, 13 Dec 2022 01:22:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234044AbiLMBWV (ORCPT ); Mon, 12 Dec 2022 20:22:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229866AbiLMBWR (ORCPT ); Mon, 12 Dec 2022 20:22:17 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE276DEBC for ; Mon, 12 Dec 2022 17:22:15 -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 ams.source.kernel.org (Postfix) with ESMTPS id 3299AB81035 for ; Tue, 13 Dec 2022 01:22:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A17AFC433EF; Tue, 13 Dec 2022 01:22:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670894532; bh=ZJutP6ZbAJukYe7JGF5sfO6MVhxr+yt4G7nFBq87jZo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lAwhBZcDdZlikyMzqmwYJu+zZE/2pqPzUUW4i5PCyKzLeW7VjKXiSV329jcLj7sbM NElbbuVxkwR+USl2XsMuAd38loBP/Z7/f+4MQYfDiIVWTD8g2vbjeFN49urS005NN6 isb5p4ALIonGVZCzNKIj+fp0IZi+gyUGVeAm+8D6ptIpEmRi65nXQFsoABVd/1Uow0 Oi1NGuiqDuFAThHrirmubYW/8E0gNd5TL7keU0m2vokpMubzb20DpJWlyXqh2HpC+6 Ho2rzzmCVvBZqranaN/Zdf66ffcQLbGTi5813MlaW2ZKOX5AfKOEOu/MuAJREz9UW9 gAF3ikn2rFdKw== Message-ID: <0cc89bf7-ea7c-d6e9-5ba9-548181de4c82@kernel.org> Date: Tue, 13 Dec 2022 09:22:09 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH v2] f2fs: add support for counting time of submit discard cmd Content-Language: en-US To: Jaegeuk Kim Cc: Yangtao Li , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org References: <20221212125137.77187-1-frank.li@vivo.com> From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/12/13 6:47, Jaegeuk Kim wrote: > 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? Agreed. Thanks, > >> >>> >>> 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;