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
given nr_shrink into multiple trials?
> 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
