Re: [PATCH v1 03/12] xprtrdma: Increase default credit limit

Devesh Sharma
2015-07-10T10:45:58Z

Increasing the default slot table entries will increase the MR
requirements per mount.

Currently, with 32 as default Client ends up allocating 2178 frmrs
(ref: kernel 4.1-rc4) for a single mount. With 128 frmr requirement
for startup would be 8448.

8K+ MRs per mount just for start-up, I am a little doubtful about this
change. We can always release-note that "for better performance
increase the slot table entries by echo 128 >
/proc/sys/sunrpc/rdma_slot_table_entries"

-Regards
Devesh

On Fri, Jul 10, 2015 at 2:12 AM, Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
> In preparation for similar increases on NFS/RDMA servers, bump the
> advertised credit limit for RPC/RDMA to 128. This allocates some
> extra resources, but the client will continue to allow only the
> number of RPCs in flight that the server requests via its advertised
> credit limit.
>
> Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> ---
> include/linux/sunrpc/xprtrdma.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/sunrpc/xprtrdma.h b/include/linux/sunrpc/xprtrdma.h
> index b176130..b7b279b 100644
> --- a/include/linux/sunrpc/xprtrdma.h
> +++ b/include/linux/sunrpc/xprtrdma.h
> @@ -49,7 +49,7 @@
> * a single chunk type per message is supported currently.
> */
> #define RPCRDMA_MIN_SLOT_TABLE (2U)
> -#define RPCRDMA_DEF_SLOT_TABLE (32U)
> +#define RPCRDMA_DEF_SLOT_TABLE (128U)
> #define RPCRDMA_MAX_SLOT_TABLE (256U)
>
> #define RPCRDMA_DEF_INLINE (1024) /* default inline max */
>
> --
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