On Fri, 2022-07-08 at 14:25 -0400, Chuck Lever wrote:
> Without LRU item rotation, the shrinker visits only a few items on
> the end of the LRU list, and those would always be long-term OPEN
> files for NFSv4 workloads. That makes the filecache shrinker
> completely ineffective.
>
> Adopt the same strategy as the inode LRU by using LRU_ROTATE.
>
> Suggested-by: Dave Chinner <david@xxxxxxxxxxxxx>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> fs/nfsd/filecache.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> index 6e9e186334ab..bd6ba63f69ae 100644
> --- a/fs/nfsd/filecache.c
> +++ b/fs/nfsd/filecache.c
> @@ -452,6 +452,7 @@ nfsd_file_dispose_list_delayed(struct list_head *dispose)
> *
> * Return values:
> * %LRU_REMOVED: @item was removed from the LRU
> + * %LRU_ROTATED: @item is to be moved to the LRU tail
%LRU_ROTATE
> * %LRU_SKIP: @item cannot be evicted
> */
> static enum lru_status
> @@ -490,7 +491,7 @@ nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru,
>
> if (test_and_clear_bit(NFSD_FILE_REFERENCED, &nf->nf_flags)) {
> trace_nfsd_file_gc_referenced(nf);
> - return LRU_SKIP;
> + return LRU_ROTATE;
> }
>
> if (!test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
> @@ -532,7 +533,7 @@ nfsd_file_gc(void)
> unsigned long ret;
>
> ret = list_lru_walk(&nfsd_file_lru, nfsd_file_lru_cb,
> - &dispose, LONG_MAX);
> + &dispose, list_lru_count(&nfsd_file_lru));
> trace_nfsd_file_gc_removed(ret, list_lru_count(&nfsd_file_lru));
> nfsd_file_gc_dispose_list(&dispose);
> }
>
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
