Re: [PATCH v2 19/22] xprtrdma: Support larger inline thresholds

[Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

> On Aug 29, 2016, at 3:52 PM, Anna Schumaker <Anna.Schumaker-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org> wrote:
> 
> Hi Chuck,
> 
> On 08/23/2016 01:54 PM, Chuck Lever wrote:
>> RPC-over-RDMA Version Two will likely require at least a 4KB inline
>> threshold by default. The Version One inline threshold is still 1KB,
>> and it's automatically negotiated down to in
>> rpcrdma_update_connect_private.
> 
> I'm curious, what is the status of RPCoRDMA v2?

There is a personal draft published:

  https://datatracker.ietf.org/doc/draft-cel-nfsv4-rpcrdma-version-two/

And being discussed actively in the nfsv4 Working Group.

The features added in this series are usable with the Linux V1 implementation
too; the point being to experiment with these new facilities before we finish
RPC-over-RDMA Version Two.


> Thanks,
> Anna
> 
>> 
>> The maximum is somewhat arbitrary. There's no fundamental
>> architectural limit I'm aware of, but it's good to keep the size of
>> Receive buffers reasonable. Now that Send can use a s/g list, a
>> Send buffer is only as large as each RPC requires. Receive buffers
>> are always the size of the inline threshold, however.
>> 
>> Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>> ---
>> include/linux/sunrpc/xprtrdma.h |    4 ++--
>> net/sunrpc/xprtrdma/transport.c |    4 ++--
>> 2 files changed, 4 insertions(+), 4 deletions(-)
>> 
>> diff --git a/include/linux/sunrpc/xprtrdma.h b/include/linux/sunrpc/xprtrdma.h
>> index 39267dc..221b7a2 100644
>> --- a/include/linux/sunrpc/xprtrdma.h
>> +++ b/include/linux/sunrpc/xprtrdma.h
>> @@ -53,8 +53,8 @@
>> #define RPCRDMA_MAX_SLOT_TABLE	(256U)
>> 
>> #define RPCRDMA_MIN_INLINE  (1024)	/* min inline thresh */
>> -#define RPCRDMA_DEF_INLINE  (1024)	/* default inline thresh */
>> -#define RPCRDMA_MAX_INLINE  (3068)	/* max inline thresh */
>> +#define RPCRDMA_DEF_INLINE  (4096)	/* default inline thresh */
>> +#define RPCRDMA_MAX_INLINE  (65536)	/* max inline thresh */
>> 
>> /* Memory registration strategies, by number.
>>  * This is part of a kernel / user space API. Do not remove. */
>> diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
>> index 6a358ab..ed5e285 100644
>> --- a/net/sunrpc/xprtrdma/transport.c
>> +++ b/net/sunrpc/xprtrdma/transport.c
>> @@ -97,7 +97,7 @@ static struct ctl_table xr_tunables_table[] = {
>> 		.data		= &xprt_rdma_max_inline_read,
>> 		.maxlen		= sizeof(unsigned int),
>> 		.mode		= 0644,
>> -		.proc_handler	= proc_dointvec,
>> +		.proc_handler	= proc_dointvec_minmax,
>> 		.extra1		= &min_inline_size,
>> 		.extra2		= &max_inline_size,
>> 	},
>> @@ -106,7 +106,7 @@ static struct ctl_table xr_tunables_table[] = {
>> 		.data		= &xprt_rdma_max_inline_write,
>> 		.maxlen		= sizeof(unsigned int),
>> 		.mode		= 0644,
>> -		.proc_handler	= proc_dointvec,
>> +		.proc_handler	= proc_dointvec_minmax,
>> 		.extra1		= &min_inline_size,
>> 		.extra2		= &max_inline_size,
>> 	},
>> 
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> 
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--
Chuck Lever



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