[PATCH v1] svcrdma: Increase the server's default RPC/RDMA credit grant

[PATCH v1] svcrdma: Increase the server's default RPC/RDMA credit grant

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Now that the nfsd thread count can scale to more threads, permit
individual clients to make more use of those threads. Increase the
RPC/RDMA per-connection credit grant from 64 to 128 -- same as the
Linux NFS client.

Simple single client fio-based benchmarking so far shows only
improvement, no regression.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/linux/sunrpc/svc_rdma.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index 22704c2e5b9b..57f4fd94166a 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -131,7 +131,7 @@ static inline struct svcxprt_rdma *svc_rdma_rqst_rdma(struct svc_rqst *rqstp)
  */
 enum {
 	RPCRDMA_LISTEN_BACKLOG	= 10,
-	RPCRDMA_MAX_REQUESTS	= 64,
+	RPCRDMA_MAX_REQUESTS	= 128,
 	RPCRDMA_MAX_BC_REQUESTS	= 2,
 };
 
-- 
2.51.0

Re: [PATCH v1] svcrdma: Increase the server's default RPC/RDMA credit grant

[Mike Snitzer]

On Fri, Sep 26, 2025 at 11:52:35AM -0400, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> Now that the nfsd thread count can scale to more threads, permit

Just trying to appreciate which change(s) paved the way for this
RPCRDMA_MAX_REQUESTS change.

Are you referring to the netlink interface changes Jeff did earlier
this year or something else? (thinking "something else" but...)

Might be useful to update the header to convey which specific
commit(s) made this change possible.

Mike

> individual clients to make more use of those threads. Increase the
> RPC/RDMA per-connection credit grant from 64 to 128 -- same as the
> Linux NFS client.
> 
> Simple single client fio-based benchmarking so far shows only
> improvement, no regression.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  include/linux/sunrpc/svc_rdma.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
> index 22704c2e5b9b..57f4fd94166a 100644
> --- a/include/linux/sunrpc/svc_rdma.h
> +++ b/include/linux/sunrpc/svc_rdma.h
> @@ -131,7 +131,7 @@ static inline struct svcxprt_rdma *svc_rdma_rqst_rdma(struct svc_rqst *rqstp)
>   */
>  enum {
>  	RPCRDMA_LISTEN_BACKLOG	= 10,
> -	RPCRDMA_MAX_REQUESTS	= 64,
> +	RPCRDMA_MAX_REQUESTS	= 128,
>  	RPCRDMA_MAX_BC_REQUESTS	= 2,
>  };
>  
> -- 
> 2.51.0
> 
> 

Re: [PATCH v1] svcrdma: Increase the server's default RPC/RDMA credit grant

[Chuck Lever]

On 10/1/25 3:35 PM, Mike Snitzer wrote:
> On Fri, Sep 26, 2025 at 11:52:35AM -0400, Chuck Lever wrote:
>> From: Chuck Lever <chuck.lever@oracle.com>
>>
>> Now that the nfsd thread count can scale to more threads, permit
> 
> Just trying to appreciate which change(s) paved the way for this
> RPCRDMA_MAX_REQUESTS change.
> 
> Are you referring to the netlink interface changes Jeff did earlier
> this year or something else? (thinking "something else" but...)
> 
> Might be useful to update the header to convey which specific
> commit(s) made this change possible.

The svc thread scaling change refers to the commits from

e3274026e2ec ("SUNRPC: move all of xprt handling into svc_xprt_handle()")

to

15d39883ee7d ("SUNRPC: change the back-channel queue to lwq")

all dated about two years ago, merged in v6.7. Just checking,
should the updated description provide more detail than that?


-- 
Chuck Lever

Re: [PATCH v1] svcrdma: Increase the server's default RPC/RDMA credit grant

[Mike Snitzer]

On Wed, Oct 01, 2025 at 04:18:10PM -0400, Chuck Lever wrote:
> On 10/1/25 3:35 PM, Mike Snitzer wrote:
> > On Fri, Sep 26, 2025 at 11:52:35AM -0400, Chuck Lever wrote:
> >> From: Chuck Lever <chuck.lever@oracle.com>
> >>
> >> Now that the nfsd thread count can scale to more threads, permit
> > 
> > Just trying to appreciate which change(s) paved the way for this
> > RPCRDMA_MAX_REQUESTS change.
> > 
> > Are you referring to the netlink interface changes Jeff did earlier
> > this year or something else? (thinking "something else" but...)
> > 
> > Might be useful to update the header to convey which specific
> > commit(s) made this change possible.
> 
> The svc thread scaling change refers to the commits from
> 
> e3274026e2ec ("SUNRPC: move all of xprt handling into svc_xprt_handle()")
> 
> to
> 
> 15d39883ee7d ("SUNRPC: change the back-channel queue to lwq")
> 
> all dated about two years ago, merged in v6.7. Just checking,
> should the updated description provide more detail than that?

No, that's perfect. Thanks