Messages in this thread | | | Date | Thu, 13 Apr 2023 08:56:10 -0700 | From | Jaegeuk Kim <> | Subject | Re: [PATCH] f2fs: fix to trigger a checkpoint in the end of foreground garbage collection |
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On 04/13, Chao Yu wrote: > On 2023/4/11 7:21, Jaegeuk Kim wrote: > > On 04/10, Chao Yu wrote: > > > On 2023/4/5 23:55, Jaegeuk Kim wrote: > > > > On 04/05, Chao Yu wrote: > > > > > On 2023/4/5 5:39, Jaegeuk Kim wrote: > > > > > > Can we do like this? > > > > > > > > > > > > From 9a58f0e59364241aa31b555cfe793d278e39b0dc Mon Sep 17 00:00:00 2001 > > > > > > From: Jaegeuk Kim <jaegeuk@kernel.org> > > > > > > Date: Tue, 4 Apr 2023 14:36:00 -0700 > > > > > > Subject: [PATCH] f2fs: do checkpoint when there's not enough free sections > > > > > > > > > > > > We didn't do checkpoint in FG_GC case, which may cause losing to reclaim prefree > > > > > > sctions in time. > > > > > > > > > > > > Fixes: 6f8d4455060d ("f2fs: avoid fi->i_gc_rwsem[WRITE] lock in f2fs_gc") > > > > > > Signed-off-by: Chao Yu <chao@kernel.org> > > > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > > > > > --- > > > > > > fs/f2fs/gc.c | 24 +++++++++++------------- > > > > > > 1 file changed, 11 insertions(+), 13 deletions(-) > > > > > > > > > > > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > > > > > > index 56c53dbe05c9..f1d0dd9c5a6c 100644 > > > > > > --- a/fs/f2fs/gc.c > > > > > > +++ b/fs/f2fs/gc.c > > > > > > @@ -1806,6 +1806,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) > > > > > > }; > > > > > > unsigned int skipped_round = 0, round = 0; > > > > > > unsigned int upper_secs; > > > > > > + bool stop_gc = false; > > > > > > trace_f2fs_gc_begin(sbi->sb, gc_type, gc_control->no_bg_gc, > > > > > > gc_control->nr_free_secs, > > > > > > @@ -1876,19 +1877,15 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) > > > > > > (gc_type == FG_GC) ? sec_freed : 0, 0)) { > > > > > > if (gc_type == FG_GC && sec_freed < gc_control->nr_free_secs) > > > > > > goto go_gc_more; > > > > > > - goto stop; > > > > > > - } > > > > > > - > > > > > > - /* FG_GC stops GC by skip_count */ > > > > > > - if (gc_type == FG_GC) { > > > > > > + stop_gc = true; > > > > > > > > > > I guess below condition is for emergency recycle of prefree segments during > > > > > foreground GC, in order to avoid exhausting free sections due to to many > > > > > metadata allocation during CP. > > > > > > > > > > if (free_sections(sbi) <= upper_secs + NR_GC_CHECKPOINT_SECS && > > > > > prefree_segments(sbi)) { > > > > > > > > > > But for common case, free_sections() is close to reserved_segments(), and > > > > > upper_secs + NR_GC_CHECKPOINT_SECS value may be far smaller than free_sections(), > > > > > so checkpoint may not be trggered as expected, IIUC. > > > > > > > > > > So it's fine to just trigger CP in the end of foreground garbage collection? > > > > > > > > My major concern is to avoid unnecessary checkpointing given multiple FG_GC > > > > requests were pending in parallel. And, I don't want to add so many combination > > > > which gives so many corner cases, and feel f2fs_gc() needs to call checkpoint > > > > automatically in the worst case scenario only. > > > > > > Alright. > > > > > > > > > > > By the way, do we just need to call checkpoint here including FG_GC as well? > > > > > > I didn't get it, do you mean? > > > > > > - f2fs_balance_fs() > > > - f2fs_gc() creates prefree segments but not call checkpoint to reclaim > > > > > > - f2fs_balance_fs() > > > - f2fs_gc() > > > - detect prefree segments created by last f2fs_balance_fs, then call > > > f2fs_write_checkpoint to reclaim > > > > > > Or could you please provide a draft patch? :-P > > > > Testing this. > > > > From ec5f37bbe33110257c04e0ec97a80b0111465b52 Mon Sep 17 00:00:00 2001 > > From: Jaegeuk Kim <jaegeuk@kernel.org> > > Date: Mon, 10 Apr 2023 14:48:50 -0700 > > Subject: [PATCH] f2fs: refactor f2fs_gc to call checkpoint in urgent condition > > > > The major change is to call checkpoint, if there's not enough space while having > > some prefree segments in FG_GC case. > > I found generic/269 will hang w/ this patch.
Yeah, I got 270 as well. I removed it in the tree first, and will check it out later.
> > Thanks, > > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > --- > > fs/f2fs/gc.c | 26 ++++++++++++-------------- > > 1 file changed, 12 insertions(+), 14 deletions(-) > > > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > > index c748cdfb0501..0a823d2e8b9d 100644 > > --- a/fs/f2fs/gc.c > > +++ b/fs/f2fs/gc.c > > @@ -1829,7 +1829,10 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) > > goto stop; > > } > > - if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0)) { > > + /* Let's run FG_GC, if we don't have enough space. */ > > + if (has_not_enough_free_secs(sbi, 0, 0)) { > > + gc_type = FG_GC; > > + > > /* > > * For example, if there are many prefree_segments below given > > * threshold, we can make them free by checkpoint. Then, we > > @@ -1840,8 +1843,6 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) > > if (ret) > > goto stop; > > } > > - if (has_not_enough_free_secs(sbi, 0, 0)) > > - gc_type = FG_GC; > > } > > /* f2fs_balance_fs doesn't need to do BG_GC in critical path. */ > > @@ -1868,19 +1869,14 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) > > if (seg_freed == f2fs_usable_segs_in_sec(sbi, segno)) > > sec_freed++; > > - if (gc_type == FG_GC) > > + if (gc_type == FG_GC) { > > sbi->cur_victim_sec = NULL_SEGNO; > > - if (gc_control->init_gc_type == FG_GC || > > - !has_not_enough_free_secs(sbi, > > - (gc_type == FG_GC) ? sec_freed : 0, 0)) { > > - if (gc_type == FG_GC && sec_freed < gc_control->nr_free_secs) > > - goto go_gc_more; > > - goto stop; > > - } > > - > > - /* FG_GC stops GC by skip_count */ > > - if (gc_type == FG_GC) { > > + if (!has_not_enough_free_secs(sbi, sec_freed, 0)) { > > + if (sec_freed < gc_control->nr_free_secs) > > + goto go_gc_more; > > + goto stop; > > + } > > if (sbi->skipped_gc_rwsem) > > skipped_round++; > > round++; > > @@ -1889,6 +1885,8 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) > > ret = f2fs_write_checkpoint(sbi, &cpc); > > goto stop; > > } > > + } else if (!has_not_enough_free_secs(sbi, 0, 0)) { > > + goto stop; > > } > > __get_secs_required(sbi, NULL, &upper_secs, NULL);
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