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b=jWS4mu0iuivW7ItJRwH3NhbAEdGlA9zSGe+Chs4J+VxXPAWbokKAeSVf6JTHT9Vva GzVk6UguJACLipIrSi7TGxXl7Pj1EpR3v0Yvp+2u74CP3F9f03bkpn6KMosHjN/OLR h0HMq6smflJBysqQy3/dOuKDeZU/15oqzN86Jn/s= Received: from epsnrtp3.localdomain (unknown [182.195.42.164]) by epcas2p2.samsung.com (KnoxPortal) with ESMTP id 20231129004830epcas2p27c67488d7b3162c3a1894db1707e582e~b8ZYC6dFL2827028270epcas2p2R; Wed, 29 Nov 2023 00:48:30 +0000 (GMT) Received: from epsmges2p4.samsung.com (unknown [182.195.36.98]) by epsnrtp3.localdomain (Postfix) with ESMTP id 4Sg10G1ymCz4x9Q0; Wed, 29 Nov 2023 00:48:30 +0000 (GMT) X-AuditID: b6c32a48-bcdfd70000002587-05-65668a5ef8d2 Received: from epcas2p2.samsung.com ( [182.195.41.54]) by epsmges2p4.samsung.com (Symantec Messaging Gateway) with SMTP id 46.8D.09607.E5A86656; Wed, 29 Nov 2023 09:48:30 +0900 (KST) Mime-Version: 1.0 From: Yonggil Song To: Chao Yu , "jaegeuk@kernel.org" , "corbet@lwn.net" , "linux-f2fs-devel@lists.sourceforge.net" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Seokhwan Kim , Daejun Park , Siwoo Jung X-Priority: 3 X-Content-Kind-Code: NORMAL In-Reply-To: X-CPGS-Detection: blocking_info_exchange X-Drm-Type: N,general X-Msg-Generator: Mail X-Msg-Type: PERSONAL X-Reply-Demand: N Message-ID: <20231129004829epcms2p424135b51305a8d006835109dcfa0f1c5@epcms2p4> Date: Wed, 29 Nov 2023 09:48:29 +0900 X-CMS-MailID: 20231129004829epcms2p424135b51305a8d006835109dcfa0f1c5 X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFupjk+LIzCtJLcpLzFFi42LZdljTTDeuKy3VYNUTbovTU88yWTw50M5o sepBuMWT9bOYLRa2LWGxuLTI3eLyrjlsFucnvmayWNUxl9GB02PTqk42j90LPjN5LO6bzOrR t2UVo8fnTXIBrFHZNhmpiSmpRQqpecn5KZl56bZK3sHxzvGmZgaGuoaWFuZKCnmJuam2Si4+ AbpumTlA5ygplCXmlAKFAhKLi5X07WyK8ktLUhUy8otLbJVSC1JyCswL9IoTc4tL89L18lJL rAwNDIxMgQoTsjNmH7nPUvAnpuL8+i/MDYwX3bsYOTkkBEwk1vb3sHUxcnEICexglFi35ilz FyMHB6+AoMTfHcIgNcIC7hJ/286zgdhCAkoS1w70skDE9SU2L17GDmKzCehK/N2wnB1kjojA RmaJaV/XMUIs4JWY0f6UBcKWlti+fCtYnFPATmL5ylXsEHENiR/LepkhbFGJm6vfssPY74/N h5ojItF67yxUjaDEg5+7oeKSEosOnWeCsPMl/q64zgZh10hsbWiDiutLXOvYCHYDr4CvRPOc nawgNouAqsTv15+gbnOR6O5rBZvJLCAvsf3tHHA4MAtoSqzfpQ9iSggoSxy5xQJRwSfRcfgv O8yHO+Y9gdqkJrF502ZWCFtG4sLjNqgrPSSm79zOBAnCXiaJ/q7qCYwKsxABPQvJ3lkIexcw Mq9iFEstKM5NTy02KjCBx21yfu4mRnDC1PLYwTj77Qe9Q4xMHIyHGCU4mJVEePU+JqcK8aYk VlalFuXHF5XmpBYfYjQF+ngis5Rocj4wZeeVxBuaWBqYmJkZmhuZGpgrifPea52bIiSQnliS mp2aWpBaBNPHxMEp1cAkt4dT7kHC9Jay1NqnbDF81Z/UAsySxCSfahxZtefEucd5B25csf6/ sGxav5XBjSNy5cezws+f5eVgbXE4/Hx/tW/GOc95U7/JOBg/X9yj0dv7dXPeIfnjP4TNbq7c yZN0eNX3GQbvz79i47T9k3T4xcacKKU51nlWzhf0T71R39td6ZG2nWPHo0lr+ThN+0NKFPKE V/j3lD9gzInMqRRePfG5WCLbOod7jsKMMx3qPZ5xdEkZzY4Ra7rI1pnyqPq4QNZfpzxtFYu4 FKHeZx+UDmZOWNHxrmV+6TsDfb+6/Q1Hde5FzC0T6Pl7y177yy1J7n4uHznVjKlLny+IubWy 63/twwKed4IV10MDXiqxFGckGmoxFxUnAgD0tm/zIQQAAA== DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20231012100345epcms2p84b95e24ee5e7965858ab8be99fbc3eff References: <20231012100345epcms2p84b95e24ee5e7965858ab8be99fbc3eff@epcms2p8> <20231026091838epcms2p46f14260fdaf53e27ee6374887ed87f41@epcms2p4> X-Headers-End: 1r89KB-0000Ze-1A Subject: Re: [f2fs-dev] (2) [PATCH v1] f2fs: New victim selection for GC X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: yonggil.song@samsung.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net >Hi Yonggil, > >On 2023/10/26 17:18, Yonggil Song wrote: >> Overview >> ======== >> >> Introduce a new way to select the data section first when selecting a >> victim in foreground GC. This victim selection method works when the >> prefer_data_victim mount option is enabled. If foreground GC migrates only >> data sections and runs out of free sections, it cleans dirty node sections >> to get more free sections. > >What about introducing parameter to adjust cost calculated by get_gc_cost()? > >Something like: > >get_gc_cost() > > if (p->gc_mode == GC_GREEDY) { > vblocks = get_valid_blocks(); > if (seg_type is data) > return vblocks * data_factor; > return vblock * node_factor; > } > >If we prefer to select data segment during fggc, we can config data/node factor >as 1 and 512? > >Thoughts? > >Thanks, > Hi Chao. I think that's a simpler way to do it. I'll work on v2 with your idea. Thanks for the feedback >> >> Problem >> ======= >> >> If the total amount of nodes is larger than the size of one section, nodes >> occupy multiple sections, and node victims are often selected because the >> gc cost is lowered by data block migration in foreground gc. Since moving >> the data section causes frequent node victim selection, victim threshing >> occurs in the node section. This results in an increase in WAF. >> >> Experiment >> ========== >> >> Test environment is as follows. >> >> System info >> - 3.6GHz, 16 core CPU >> - 36GiB Memory >> Device info >> - a conventional null_blk with 228MiB >> - a sequential null_blk with 4068 zones of 8MiB >> Format >> - mkfs.f2fs -c -m -Z 8 -o 3.89 >> Mount >> - mount -o prefer_data_victim >> Fio script >> - fio --rw=randwrite --bs=4k --ba=4k --filesize=31187m --norandommap --overwrite=1 --name=job1 --filename=./mnt/sustain --io_size=128g >> WAF calculation >> - (IOs on conv. null_blk + IOs on seq. null_blk) / random write IOs >> >> Conclusion >> ========== >> >> This experiment showed that the WAF was reduced by 29% (18.75 -> 13.3) when >> the data section was selected first when selecting GC victims. This was >> achieved by reducing the migration of the node blocks by 69.4% >> (253,131,743 blks -> 77,463,278 blks). It is possible to achieve low WAF >> performance with the GC victim selection method in environments where the >> section size is relatively small. >> >> Signed-off-by: Yonggil Song >> --- >> Documentation/filesystems/f2fs.rst | 3 + >> fs/f2fs/f2fs.h | 2 + >> fs/f2fs/gc.c | 100 +++++++++++++++++++++++------ >> fs/f2fs/segment.h | 2 + >> fs/f2fs/super.c | 9 +++ >> 5 files changed, 95 insertions(+), 21 deletions(-) >> >> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst >> index d32c6209685d..58e6d001d7ab 100644 >> --- a/Documentation/filesystems/f2fs.rst >> +++ b/Documentation/filesystems/f2fs.rst >> @@ -367,6 +367,9 @@ errors=%s Specify f2fs behavior on critical errors. This supports modes: >> pending node write drop keep N/A >> pending meta write keep keep N/A >> ====================== =============== =============== ======== >> +prefer_data_victim When selecting victims in foreground GC, victims of data type >> + are prioritized. This option minimizes GC victim threshing >> + in the node section to reduce WAF. >> ======================== ============================================================ >> >> Debugfs Entries >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >> index 6d688e42d89c..8b31fa2ea09a 100644 >> --- a/fs/f2fs/f2fs.h >> +++ b/fs/f2fs/f2fs.h >> @@ -108,6 +108,7 @@ extern const char *f2fs_fault_name[FAULT_MAX]; >> #define F2FS_MOUNT_GC_MERGE 0x02000000 >> #define F2FS_MOUNT_COMPRESS_CACHE 0x04000000 >> #define F2FS_MOUNT_AGE_EXTENT_CACHE 0x08000000 >> +#define F2FS_MOUNT_PREFER_DATA_VICTIM 0x10000000 >> >> #define F2FS_OPTION(sbi) ((sbi)->mount_opt) >> #define clear_opt(sbi, option) (F2FS_OPTION(sbi).opt &= ~F2FS_MOUNT_##option) >> @@ -1648,6 +1649,7 @@ struct f2fs_sb_info { >> struct f2fs_mount_info mount_opt; /* mount options */ >> >> /* for cleaning operations */ >> + bool need_node_clean; /* only used for prefer_data_victim */ >> struct f2fs_rwsem gc_lock; /* >> * semaphore for GC, avoid >> * race between GC and GC or CP >> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >> index f550cdeaa663..8a2da808a5fb 100644 >> --- a/fs/f2fs/gc.c >> +++ b/fs/f2fs/gc.c >> @@ -752,6 +752,8 @@ int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result, >> unsigned int last_segment; >> unsigned int nsearched; >> bool is_atgc; >> + bool is_prefer_data_victim = >> + test_opt(sbi, PREFER_DATA_VICTIM) && gc_type == FG_GC; >> int ret = 0; >> >> mutex_lock(&dirty_i->seglist_lock); >> @@ -767,6 +769,11 @@ int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result, >> p.oldest_age = 0; >> p.min_cost = get_max_cost(sbi, &p); >> >> + if (is_prefer_data_victim) { >> + p.node_min_cost = p.min_cost; >> + p.node_min_segno = p.min_segno; >> + } >> + >> is_atgc = (p.gc_mode == GC_AT || p.alloc_mode == AT_SSR); >> nsearched = 0; >> >> @@ -884,9 +891,25 @@ int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result, >> >> cost = get_gc_cost(sbi, segno, &p); >> >> - if (p.min_cost > cost) { >> - p.min_segno = segno; >> - p.min_cost = cost; >> + if (is_prefer_data_victim) { >> + if (IS_DATASEG(get_seg_entry(sbi, segno)->type)) { >> + /* update data segments victim */ >> + if (p.min_cost > cost) { >> + p.min_segno = segno; >> + p.min_cost = cost; >> + } >> + } else { >> + /* update node segments victim */ >> + if (p.node_min_cost > cost) { >> + p.node_min_segno = segno; >> + p.node_min_cost = cost; >> + } >> + } >> + } else { >> + if (p.min_cost > cost) { >> + p.min_segno = segno; >> + p.min_cost = cost; >> + } >> } >> next: >> if (nsearched >= p.max_search) { >> @@ -901,6 +924,25 @@ int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result, >> } >> } >> >> + if (is_prefer_data_victim && sbi->need_node_clean) { >> + /* we need to clean node sections */ >> + if (p.min_cost > p.node_min_cost) { >> + p.min_segno = p.node_min_segno; >> + p.min_cost = p.node_min_cost; >> + } else { >> + /* >> + * data victim cost is the lowest. >> + * if free sections are enough, stop cleaning node victim. >> + * if not, it goes on by GCing data victims. >> + */ >> + if (has_enough_free_secs(sbi, prefree_segments(sbi), 0)) { >> + sbi->need_node_clean = false; >> + p.min_segno = NULL_SEGNO; >> + goto out; >> + } >> + } >> + } >> + >> /* get victim for GC_AT/AT_SSR */ >> if (is_atgc) { >> lookup_victim_by_age(sbi, &p); >> @@ -1830,8 +1872,27 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) >> goto stop; >> } >> >> + __get_secs_required(sbi, NULL, &upper_secs, NULL); >> + >> + /* >> + * Write checkpoint to reclaim prefree segments. >> + * We need more three extra sections for writer's data/node/dentry. >> + */ >> + if (free_sections(sbi) <= upper_secs + NR_GC_CHECKPOINT_SECS) { >> + if (test_opt(sbi, PREFER_DATA_VICTIM)) { >> + sbi->need_node_clean = true; >> + } >> + if (prefree_segments(sbi)) { >> + ret = f2fs_write_checkpoint(sbi, &cpc); >> + if (ret) >> + goto stop; >> + /* Reset due to checkpoint */ >> + sec_freed = 0; >> + } >> + } >> + >> /* Let's run FG_GC, if we don't have enough space. */ >> - if (has_not_enough_free_secs(sbi, 0, 0)) { >> + if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0)) { >> gc_type = FG_GC; >> >> /* >> @@ -1882,7 +1943,17 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) >> if (!gc_control->no_bg_gc && >> total_sec_freed < gc_control->nr_free_secs) >> goto go_gc_more; >> - goto stop; >> + if (test_opt(sbi, PREFER_DATA_VICTIM)) { >> + /* >> + * If the need_node_clean flag is set >> + * even though there are enough free >> + * sections, node cleaning will continue. >> + */ >> + if (!sbi->need_node_clean) >> + goto stop; >> + } else { >> + goto stop; >> + } >> } >> if (sbi->skipped_gc_rwsem) >> skipped_round++; >> @@ -1897,21 +1968,6 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) >> goto stop; >> } >> >> - __get_secs_required(sbi, NULL, &upper_secs, NULL); >> - >> - /* >> - * Write checkpoint to reclaim prefree segments. >> - * We need more three extra sections for writer's data/node/dentry. >> - */ >> - if (free_sections(sbi) <= upper_secs + NR_GC_CHECKPOINT_SECS && >> - prefree_segments(sbi)) { >> - stat_inc_cp_call_count(sbi, TOTAL_CALL); >> - ret = f2fs_write_checkpoint(sbi, &cpc); >> - if (ret) >> - goto stop; >> - /* Reset due to checkpoint */ >> - sec_freed = 0; >> - } >> go_gc_more: >> segno = NULL_SEGNO; >> goto gc_more; >> @@ -1920,8 +1976,10 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) >> SIT_I(sbi)->last_victim[ALLOC_NEXT] = 0; >> SIT_I(sbi)->last_victim[FLUSH_DEVICE] = gc_control->victim_segno; >> >> - if (gc_type == FG_GC) >> + if (gc_type == FG_GC) { >> f2fs_unpin_all_sections(sbi, true); >> + sbi->need_node_clean = false; >> + } >> >> trace_f2fs_gc_end(sbi->sb, ret, total_freed, total_sec_freed, >> get_pages(sbi, F2FS_DIRTY_NODES), >> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h >> index 2ca8fb5d0dc4..d55fa1fee2e0 100644 >> --- a/fs/f2fs/segment.h >> +++ b/fs/f2fs/segment.h >> @@ -197,8 +197,10 @@ struct victim_sel_policy { >> unsigned int offset; /* last scanned bitmap offset */ >> unsigned int ofs_unit; /* bitmap search unit */ >> unsigned int min_cost; /* minimum cost */ >> + unsigned int node_min_cost; /* minimum cost of node type section */ >> unsigned long long oldest_age; /* oldest age of segments having the same min cost */ >> unsigned int min_segno; /* segment # having min. cost */ >> + unsigned int node_min_segno; /* node segment # having min. cost */ >> unsigned long long age; /* mtime of GCed section*/ >> unsigned long long age_threshold;/* age threshold */ >> }; >> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c >> index a8c8232852bb..133137dd6fd0 100644 >> --- a/fs/f2fs/super.c >> +++ b/fs/f2fs/super.c >> @@ -165,6 +165,7 @@ enum { >> Opt_memory_mode, >> Opt_age_extent_cache, >> Opt_errors, >> + Opt_prefer_data_victim, >> Opt_err, >> }; >> >> @@ -245,6 +246,7 @@ static match_table_t f2fs_tokens = { >> {Opt_memory_mode, "memory=%s"}, >> {Opt_age_extent_cache, "age_extent_cache"}, >> {Opt_errors, "errors=%s"}, >> + {Opt_prefer_data_victim, "prefer_data_victim"}, >> {Opt_err, NULL}, >> }; >> >> @@ -1286,6 +1288,13 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount) >> } >> kfree(name); >> break; >> + case Opt_prefer_data_victim: >> + if (!f2fs_sb_has_blkzoned(sbi)) { >> + f2fs_err(sbi, "prefer_data_victim is only allowed with zoned block device feature"); >> + return -EINVAL; >> + } >> + set_opt(sbi, PREFER_DATA_VICTIM); >> + break; >> default: >> f2fs_err(sbi, "Unrecognized mount option \"%s\" or missing value", >> p); _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel