Re: [PATCH v4 14/14] SUNRPC: Bump the maximum payload size for the server

Jeff Layton
2025-04-28T21:08:43Z

On Mon, 2025-04-28 at 15:37 -0400, cel@kernel.org wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
>
> Increase the maximum server-side RPC payload to 4MB. The default
> remains at 1MB.
>
> To adjust the operational maximum, shut down the NFS server. Then
> echo a new value into:
>
> /proc/fs/nfsd/max_block_size
>
> And restart the NFS server.
>
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> include/linux/sunrpc/svc.h | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
> index e27bc051ec67..b449eb02e00a 100644
> --- a/include/linux/sunrpc/svc.h
> +++ b/include/linux/sunrpc/svc.h
> @@ -119,14 +119,14 @@ void svc_destroy(struct svc_serv **svcp);
> * Linux limit; someone who cares more about NFS/UDP performance
> * can test a larger number.
> *
> - * For TCP transports we have more freedom. A size of 1MB is
> - * chosen to match the client limit. Other OSes are known to
> - * have larger limits, but those numbers are probably beyond
> - * the point of diminishing returns.
> + * For non-UDP transports we have more freedom. A size of 4MB is
> + * chosen to accommodate clients that support larger I/O sizes.
> */
> -#define RPCSVC_MAXPAYLOAD (1*1024*1024u)
> -#define RPCSVC_MAXPAYLOAD_TCP RPCSVC_MAXPAYLOAD
> -#define RPCSVC_MAXPAYLOAD_UDP (32*1024u)
> +enum {
> + RPCSVC_MAXPAYLOAD = 4 * 1024 * 1024,
> + RPCSVC_MAXPAYLOAD_TCP = RPCSVC_MAXPAYLOAD,
> + RPCSVC_MAXPAYLOAD_UDP = 32 * 1024,
> +};

I guess the enum is so that the symbol names remain in debuginfo?

>
> extern u32 svc_max_payload(const struct svc_rqst *rqstp);
>

Reviewed-by: Jeff Layton <jlayton@kernel.org>