On 05/07, Chao Yu wrote:
> On 2020/5/6 23:05, Jaegeuk Kim wrote:
> > On 05/06, Chao Yu wrote:
> >> In f2fs_try_to_free_nids(), .nid_list_lock spinlock critical region will
> >> increase as expected shrink number increase, to avoid spining other CPUs
> >> for long time, it's better to implement like extent cache and nats
> >> shrinker.
> >>
> >> Signed-off-by: Chao Yu <yuch...@huawei.com>
> >> ---
> >> v2:
> >> - fix unlock wrong spinlock.
> >> fs/f2fs/node.c | 15 +++++++++++----
> >> 1 file changed, 11 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> >> index 4da0d8713df5..ad0b14f4dab8 100644
> >> --- a/fs/f2fs/node.c
> >> +++ b/fs/f2fs/node.c
> >> @@ -2488,7 +2488,6 @@ void f2fs_alloc_nid_failed(struct f2fs_sb_info *sbi,
> >> nid_t nid)
> >> int f2fs_try_to_free_nids(struct f2fs_sb_info *sbi, int nr_shrink)
> >> {
> >> struct f2fs_nm_info *nm_i = NM_I(sbi);
> >> - struct free_nid *i, *next;
> >> int nr = nr_shrink;
> >>
> >> if (nm_i->nid_cnt[FREE_NID] <= MAX_FREE_NIDS)
> >> @@ -2498,14 +2497,22 @@ int f2fs_try_to_free_nids(struct f2fs_sb_info
> >> *sbi, int nr_shrink)
> >> return 0;
> >>
> >> spin_lock(&nm_i->nid_list_lock);
> >> - list_for_each_entry_safe(i, next, &nm_i->free_nid_list, list) {
> >> - if (nr_shrink <= 0 ||
> >> - nm_i->nid_cnt[FREE_NID] <= MAX_FREE_NIDS)
> >> + while (nr_shrink) {
> >> + struct free_nid *i;
> >> +
> >> + if (nm_i->nid_cnt[FREE_NID] <= MAX_FREE_NIDS)
> >> break;
> >>
> >> + i = list_first_entry(&nm_i->free_nid_list,
> >> + struct free_nid, list);
> >> + list_del(&i->list);
> >> + spin_unlock(&nm_i->nid_list_lock);
> >> +
> >> __remove_free_nid(sbi, i, FREE_NID);
> >
> > __remove_free_nid() will do list_del again. btw, how about just splitting
> > out
>
> Oh, my bad.
>
> How about moving __remove_free_nid into .nid_list_lock coverage?
>
> > given nr_shrink into multiple trials?
>
> Like this?
Yes.
>
> while (shrink) {
> batch = DEFAULT_BATCH_NUMBER; // 16
> spinlock();
> list_for_each_entry_safe() {
> if (!shrink || !batch)
> break;
> remove_item_from_list;
> shrink--;
> batch--;
> }
> spin_unlock();
> }
>
> Thanks,
>
> >
> >> kmem_cache_free(free_nid_slab, i);
> >> nr_shrink--;
> >> +
> >> + spin_lock(&nm_i->nid_list_lock);
> >> }
> >> spin_unlock(&nm_i->nid_list_lock);
> >> mutex_unlock(&nm_i->build_lock);
> >> --
> >> 2.18.0.rc1
> > .
> >
