Messages in this thread | | | Date | Thu, 13 Apr 2023 17:15:46 +0800 | Subject | Re: [PATCH] f2fs: fix to trigger a checkpoint in the end of foreground garbage collection | From | Chao Yu <> |
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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.
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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