[PATCH] fs: nfs: Decrease NFS timeout

[Sascha Hauer]

Hi Uwe,

On Wed, May 26, 2021 at 11:44:48AM +0200, Uwe Kleine-König wrote:
> On a customer site we're experience a bit over 1% UDP packet loss. When
> wiresharking an NFS transfer of a kernel image (with the goal to boot
> via NFS) I saw 64 of 2555 RPC calls staying unanswered. With the current
> timeout setting each of them introduces a delay of 2 seconds and the
> whole transfer takes 137s. With the timeout reduced to 0.1s the transfer
> time is not optimal (going down to approx 15 seconds) but at least it
> becomes bearable.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
> ---
>  fs/nfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/nfs.c b/fs/nfs.c
> index 1130632eb3eb..1ff81a5ee1bf 100644
> --- a/fs/nfs.c
> +++ b/fs/nfs.c
> @@ -119,7 +119,7 @@ struct rpc_reply {
>  	uint32_t data[0];
>  };
>  
> -#define NFS_TIMEOUT	(2 * SECOND)
> +#define NFS_TIMEOUT	(100 * MSECOND)
>  #define NFS_MAX_RESEND	5

Should we increase NFS_MAX_RESEND at the same time? Otherwise we timeout
after 500ms which doesn't seem much to me on some network hickups.

Sascha

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