On Wed, Jun 22, 2022 at 10:15:56AM -0400, Chuck Lever wrote:
> Enable the filecache hash table to start small, then grow with the
> workload. Smaller server deployments benefit because there should
> be lower memory utilization. Larger server deployments should see
> improved scaling with the number of open files.
>
> I know this is a big and messy patch, but there's no good way to
> rip out and replace a data structure like this.
>
> Suggested-by: Jeff Layton <jlayton@xxxxxxxxxx>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Pretty sure I mentioned converting to rhashtable as well when we
were talking about the pointer-chasing overhead of list and tree
based indexing of large caches. :)
> +
> +/*
> + * Atomically insert a new nfsd_file item into nfsd_file_rhash_tbl.
> + *
> + * Return values:
> + * %NULL: @new was inserted successfully
> + * %A valid pointer: @new was not inserted, a matching item is returned
> + * %ERR_PTR: an unexpected error occurred during insertion
> + */
> +static struct nfsd_file *nfsd_file_insert(struct nfsd_file *new)
> +{
> + struct nfsd_file_lookup_key key = {
> + .type = NFSD_FILE_KEY_FULL,
> + .inode = new->nf_inode,
> + .need = new->nf_flags,
> + .net = new->nf_net,
> + .cred = current_cred(),
> + };
> + struct nfsd_file *nf;
> +
> + nf = rhashtable_lookup_get_insert_key(&nfsd_file_rhash_tbl,
> + &key, &new->nf_rhash,
> + nfsd_file_rhash_params);
> + if (!nf)
> + return nf;
The insert can return an error (e.g. -ENOMEM) so need to check
IS_ERR(nf) here as well.
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
