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Message-ID: <20250415235828.2045-1-yohan.joung@sk.com>
Date: Wed, 16 Apr 2025 08:58:23 +0900
From: "yohan.joung" <yohan.joung@...com>
To: daeho43@...il.com
Cc: chao@...nel.org,
jaegeuk@...nel.org,
linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org,
pilhyun.kim@...com
Subject: Re: [f2fs-dev] [PATCH v1] f2fs: Improve large section GC by locating valid block segments
>On Fri, Apr 11, 2025 at 3:07 AM Chao Yu <chao@...nel.org> wrote:
>>
>> Yohan,
>>
>> Sorry for the delay, will catch up this a little bit latter.
>>
>> On 2025/4/10 8:17, yohan.joung wrote:
>> > hi jeageuk, chao
>> > How about changing the large section gc in this direction?
>> > Thanks
>> >
>> >> Change the large section GC to locate valid block segments instead of
>> >> performing a sequential search. This modification enhances performance
>> >> by reducing unnecessary block scanning in large storage sections.
>> >>
>> >> example :
>> >> [invalid seg 0] [invalid seg 1] [invalid seg 2]
>> >> [ valid seg 3] [ valid seg 4] [ valid seg 5]
>> >>
>> >> Current: In the first GC, nothing is moved,
>> >> but in the second GC, segments 3, 4, and 5 are moved.
>> >> Change: In the first GC, segments 3, 4, and 5 are moved.
>> >>
>> >> Signed-off-by: yohan.joung <yohan.joung@...com>
>> >> ---
>> >> fs/f2fs/f2fs.h | 2 ++
>> >> fs/f2fs/gc.c | 92 +++++++++++++++++++++++++++++++++++--------------
>> >> fs/f2fs/gc.h | 6 ++++
>> >> fs/f2fs/super.c | 8 ++++-
>> >> 4 files changed, 82 insertions(+), 26 deletions(-)
>> >>
>> >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> >> index f1576dc6ec67..348417edac25 100644
>> >> --- a/fs/f2fs/f2fs.h
>> >> +++ b/fs/f2fs/f2fs.h
>> >> @@ -4008,6 +4008,8 @@ int f2fs_gc_range(struct f2fs_sb_info *sbi,
>> >> int f2fs_resize_fs(struct file *filp, __u64 block_count);
>> >> int __init f2fs_create_garbage_collection_cache(void);
>> >> void f2fs_destroy_garbage_collection_cache(void);
>> >> +int __init f2fs_init_garbage_collection_summary_cache(void);
>> >> +void f2fs_destroy_garbage_collection_summary_cache(void);
>> >> /* victim selection function for cleaning and SSR */
>> >> int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result,
>> >> int gc_type, int type, char alloc_mode,
>> >> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> >> index 2b8f9239bede..3b63e85fa038 100644
>> >> --- a/fs/f2fs/gc.c
>> >> +++ b/fs/f2fs/gc.c
>> >> @@ -24,6 +24,7 @@
>> >> #include <trace/events/f2fs.h>
>> >>
>> >> static struct kmem_cache *victim_entry_slab;
>> >> +static struct kmem_cache *gc_page_entry_slab;
>> >>
>> >> static unsigned int count_bits(const unsigned long *addr,
>> >> unsigned int offset, unsigned int len);
>> >> @@ -711,6 +712,30 @@ static void release_victim_entry(struct f2fs_sb_info *sbi)
>> >> f2fs_bug_on(sbi, !list_empty(&am->victim_list));
>> >> }
>> >>
>> >> +static struct gc_page_entry *add_gc_page_entry(struct list_head *gc_page_list,
>> >> + struct page *sum_page, unsigned int segno)
>> >> +{
>> >> + struct gc_page_entry *gpe;
>> >> +
>> >> + gpe = f2fs_kmem_cache_alloc(gc_page_entry_slab, GFP_NOFS, true, NULL);
>> >> + gpe->segno = segno;
>> >> + gpe->sum_page = sum_page;
>> >> + list_add_tail(&gpe->list, gc_page_list);
>> >> + return gpe;
>> >> +}
>> >> +
>> >> +static void release_gc_page_entry(struct list_head *gc_page_list, bool putpage)
>> >> +{
>> >> + struct gc_page_entry *gpe, *tmp;
>> >> +
>> >> + list_for_each_entry_safe(gpe, tmp, gc_page_list, list) {
>> >> + if (putpage)
>> >> + f2fs_put_page(gpe->sum_page, 0);
>> >> + list_del(&gpe->list);
>> >> + kmem_cache_free(gc_page_entry_slab, gpe);
>> >> + }
>> >> +}
>> >> +
>> >> static bool f2fs_pin_section(struct f2fs_sb_info *sbi, unsigned int segno)
>> >> {
>> >> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
>> >> @@ -1721,14 +1746,18 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>> >> struct page *sum_page;
>> >> struct f2fs_summary_block *sum;
>> >> struct blk_plug plug;
>> >> + struct gc_page_entry *gpe;
>> >> unsigned int segno = start_segno;
>> >> unsigned int end_segno = start_segno + SEGS_PER_SEC(sbi);
>> >> unsigned int sec_end_segno;
>> >> + unsigned int window_granularity = 1;
>> >> int seg_freed = 0, migrated = 0;
>> >> unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
>> >> SUM_TYPE_DATA : SUM_TYPE_NODE;
>> >> unsigned char data_type = (type == SUM_TYPE_DATA) ? DATA : NODE;
>> >> int submitted = 0;
>> >> + int gc_list_count = 0;
>> >> + LIST_HEAD(gc_page_list);
>> >>
>> >> if (__is_large_section(sbi)) {
>> >> sec_end_segno = rounddown(end_segno, SEGS_PER_SEC(sbi));
>> >> @@ -1744,7 +1773,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>> >> f2fs_usable_segs_in_sec(sbi);
>> >>
>> >> if (gc_type == BG_GC || one_time) {
>> >> - unsigned int window_granularity =
>> >> + window_granularity =
>> >> sbi->migration_window_granularity;
>
>Plz, refer to the below described in sysfs-fs-f2fs.
Thanks, I'll take a look at this.
>
>What: /sys/fs/f2fs/<disk>/migration_window_granularity
>Date: September 2024
>Contact: "Daeho Jeong" <daehojeong@...gle.com>
>Description: Controls migration window granularity of garbage
>collection on large
> section. it can control the scanning window
>granularity for GC migration
> in a unit of segment, while migration_granularity
>controls the number
> of segments which can be migrated at the same turn.
>
>In your patch, it's more like migration_granularity.
>Plus, I think we don't need migration_window_granularity anymore with
>your patch.
>
>> >>
>> >> if (f2fs_sb_has_blkzoned(sbi) &&
>> >> @@ -1752,8 +1781,6 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>> >> sbi->gc_thread->boost_zoned_gc_percent))
>> >> window_granularity *=
>> >> BOOST_GC_MULTIPLE;
>> >> -
>> >> - end_segno = start_segno + window_granularity;
>> >> }
>> >>
>> >> if (end_segno > sec_end_segno)
>> >> @@ -1762,37 +1789,38 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>> >>
>> >> sanity_check_seg_type(sbi, get_seg_entry(sbi, segno)->type);
>> >>
>> >> - /* readahead multi ssa blocks those have contiguous address */
>> >> - if (__is_large_section(sbi))
>> >> + for (segno = start_segno; segno < end_segno; segno++) {
>> >> + if (!get_valid_blocks(sbi, segno, false))
>> >> + continue;
>> >> +
>> >> + /* readahead multi ssa blocks those have contiguous address */
>> >> f2fs_ra_meta_pages(sbi, GET_SUM_BLOCK(sbi, segno),
>> >> - end_segno - segno, META_SSA, true);
>> >> + window_granularity, META_SSA, true);
>> >>
>> >> - /* reference all summary page */
>> >> - while (segno < end_segno) {
>> >> - sum_page = f2fs_get_sum_page(sbi, segno++);
>> >> + /* reference all summary page */
>> >> + sum_page = f2fs_get_sum_page(sbi, segno);
>> >> if (IS_ERR(sum_page)) {
>> >> int err = PTR_ERR(sum_page);
>> >> -
>> >> - end_segno = segno - 1;
>> >> - for (segno = start_segno; segno < end_segno; segno++) {
>> >> - sum_page = find_get_page(META_MAPPING(sbi),
>> >> - GET_SUM_BLOCK(sbi, segno));
>> >> - f2fs_put_page(sum_page, 0);
>> >> - f2fs_put_page(sum_page, 0);
>> >> - }
>> >> + release_gc_page_entry(&gc_page_list, true);
>> >> return err;
>> >> }
>> >> + add_gc_page_entry(&gc_page_list, sum_page, segno);
>> >> unlock_page(sum_page);
>> >> + if (++gc_list_count >= window_granularity)
>> >> + break;
>> >> }
>> >>
>> >> blk_start_plug(&plug);
>> >>
>> >> - for (segno = start_segno; segno < end_segno; segno++) {
>> >> + list_for_each_entry(gpe, &gc_page_list, list) {
>> >>
>> >> /* find segment summary of victim */
>> >> - sum_page = find_get_page(META_MAPPING(sbi),
>> >> - GET_SUM_BLOCK(sbi, segno));
>> >> - f2fs_put_page(sum_page, 0);
>> >> + sum_page = gpe->sum_page;
>> >> + segno = gpe->segno;
>> >> + if (!sum_page) {
>> >> + f2fs_err(sbi, "Failed to get summary page for segment %u", segno);
>> >> + goto skip;
>> >> + }
>> >>
>> >> if (get_valid_blocks(sbi, segno, false) == 0)
>> >> goto freed;
>> >> @@ -1835,18 +1863,20 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>> >> get_valid_blocks(sbi, segno, false) == 0)
>> >> seg_freed++;
>> >>
>> >> - if (__is_large_section(sbi))
>> >> - sbi->next_victim_seg[gc_type] =
>> >> - (segno + 1 < sec_end_segno) ?
>> >> - segno + 1 : NULL_SEGNO;
>> >> skip:
>> >> f2fs_put_page(sum_page, 0);
>> >> }
>> >>
>> >> + if (__is_large_section(sbi) && !list_empty(&gc_page_list))
>> >> + sbi->next_victim_seg[gc_type] =
>> >> + (segno + 1 < sec_end_segno) ?
>> >> + segno + 1 : NULL_SEGNO;
>> >> +
>> >> if (submitted)
>> >> f2fs_submit_merged_write(sbi, data_type);
>> >>
>> >> blk_finish_plug(&plug);
>> >> + release_gc_page_entry(&gc_page_list, false);
>> >>
>> >> if (migrated)
>> >> stat_inc_gc_sec_count(sbi, data_type, gc_type);
>> >> @@ -2008,6 +2038,18 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
>> >> return ret;
>> >> }
>> >>
>> >> +int __init f2fs_init_garbage_collection_summary_cache(void)
>> >> +{
>> >> + gc_page_entry_slab = f2fs_kmem_cache_create("f2fs_gc_page_entry",
>> >> + sizeof(struct gc_page_entry));
>> >> + return gc_page_entry_slab ? 0 : -ENOMEM;
>> >> +}
>> >> +
>> >> +void f2fs_destroy_garbage_collection_summary_cache(void)
>> >> +{
>> >> + kmem_cache_destroy(gc_page_entry_slab);
>> >> +}
>> >> +
>> >> int __init f2fs_create_garbage_collection_cache(void)
>> >> {
>> >> victim_entry_slab = f2fs_kmem_cache_create("f2fs_victim_entry",
>> >> diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
>> >> index 5c1eaf55e127..9c8695efe394 100644
>> >> --- a/fs/f2fs/gc.h
>> >> +++ b/fs/f2fs/gc.h
>> >> @@ -82,6 +82,12 @@ struct victim_entry {
>> >> struct list_head list;
>> >> };
>> >>
>> >> +struct gc_page_entry {
>> >> + unsigned int segno;
>> >> + struct page *sum_page;
>> >> + struct list_head list;
>> >> +};
>> >> +
>> >> /*
>> >> * inline functions
>> >> */
>> >> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> >> index f087b2b71c89..a3241730fe4f 100644
>> >> --- a/fs/f2fs/super.c
>> >> +++ b/fs/f2fs/super.c
>> >> @@ -5090,9 +5090,12 @@ static int __init init_f2fs_fs(void)
>> >> err = f2fs_create_garbage_collection_cache();
>> >> if (err)
>> >> goto free_extent_cache;
>> >> - err = f2fs_init_sysfs();
>> >> + err = f2fs_init_garbage_collection_summary_cache();
>> >> if (err)
>> >> goto free_garbage_collection_cache;
>> >> + err = f2fs_init_sysfs();
>> >> + if (err)
>> >> + goto free_garbage_collection_summary_cache;
>> >> err = f2fs_init_shrinker();
>> >> if (err)
>> >> goto free_sysfs;
>> >> @@ -5141,6 +5144,8 @@ static int __init init_f2fs_fs(void)
>> >> f2fs_exit_shrinker();
>> >> free_sysfs:
>> >> f2fs_exit_sysfs();
>> >> +free_garbage_collection_summary_cache:
>> >> + f2fs_destroy_garbage_collection_summary_cache();
>> >> free_garbage_collection_cache:
>> >> f2fs_destroy_garbage_collection_cache();
>> >> free_extent_cache:
>> >> @@ -5172,6 +5177,7 @@ static void __exit exit_f2fs_fs(void)
>> >> f2fs_destroy_root_stats();
>> >> f2fs_exit_shrinker();
>> >> f2fs_exit_sysfs();
>> >> + f2fs_destroy_garbage_collection_summary_cache();
>> >> f2fs_destroy_garbage_collection_cache();
>> >> f2fs_destroy_extent_cache();
>> >> f2fs_destroy_recovery_cache();
>> >> --
>> >> 2.33.0
>> >>
>
>Do you have any numbers showing how much the performance is enhanced?
Depending on the valid block count within a section,
in the worst-case scenario, it is assumed that only
the last 3 segments in the section are valid (SEGS_PER_SEC 512)
#define DEF_GC_THREAD_MAX_SLEEP_TIME_ZONED 20
#define DEF_MIGRATION_WINDOW_GRANULARITY_ZONED 3
The time required to move a single section
before :
170 * 20ms + migrate 3segments
after :
migrate 3segments
Thanks.
>
>Thanks.
>
>> >>
>> >>
>> >> _______________________________________________
>> >> Linux-f2fs-devel mailing list
>> >> Linux-f2fs-devel@...ts.sourceforge.net
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