2008-09-04 15:00:04

by Scott Atchley

Subject: XPRTRDMA max payload?

Hi all,

I thought that the max payload for XPRTRDMA would be 1 MB. It seems to
be set on the client to 23 KB (RPCRDMA_MAX_DATA_SEGS * PAGE_SIZE). The
server, on the other hand, sets it to 1 MB (RPCSVC_MAXPAYLOAD_TCP).

If I try to mount with rdma with:

# mount.nfs host:/exports /mnt/test -o
rdma,port=2050,rsize=1048576,wsize=1048576

It ignores the size parameters and /proc/mounts shows it is 32 KB.

Is there a way to increase it at loadtime or runtime or do I need to
change RPCRDMA_MAX_DATA_SEGS and recompile?

Thanks,

Scott

2008-09-04 15:03:34

by Scott Atchley

Subject: Re: XPRTRDMA max payload?

On Sep 4, 2008, at 11:00 AM, Scott Atchley wrote:

> It seems to be set on the client to 23 KB (RPCRDMA_MAX_DATA_SEGS *
> PAGE_SIZE).

s/23/32/

:-P

2008-09-04 15:45:09

by Jim Schutt

Subject: Re: XPRTRDMA max payload?

Scott Atchley <atchley@...> writes:

>
> Hi all,
>
> I thought that the max payload for XPRTRDMA would be 1 MB. It seems to
> be set on the client to 23 KB (RPCRDMA_MAX_DATA_SEGS * PAGE_SIZE). The
> server, on the other hand, sets it to 1 MB (RPCSVC_MAXPAYLOAD_TCP).
>
> If I try to mount with rdma with:
>
> # mount.nfs host:/exports /mnt/test -o
> rdma,port=2050,rsize=1048576,wsize=1048576
>
> It ignores the size parameters and /proc/mounts shows it is 32 KB.
>
> Is there a way to increase it at loadtime or runtime or do I need to
> change RPCRDMA_MAX_DATA_SEGS and recompile?

That's the only way I was able to find to do it.

You'll want this patch also:
http://marc.info/?l=linux-nfs&m=121936891515202&w=2

There are some things on the stack dimensioned by
RPCRDMA_MAX_DATA_SEGS. I've not encountered any
problems using 16 for RPCRDMA_MAX_DATA_SEGS,
but I've not tried anything bigger.

-- Jim


>
> Thanks,
>
> Scott
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2008-09-04 16:00:14

by Scott Atchley

Subject: Re: XPRTRDMA max payload?

On Sep 4, 2008, at 11:39 AM, Jim Schutt wrote:

> That's the only way I was able to find to do it.
>
> You'll want this patch also:
> http://marc.info/?l=linux-nfs&m=121936891515202&w=2
>
> There are some things on the stack dimensioned by
> RPCRDMA_MAX_DATA_SEGS. I've not encountered any
> problems using 16 for RPCRDMA_MAX_DATA_SEGS,
> but I've not tried anything bigger.
>
> -- Jim

Hi Jim,

Thanks for the patch and the confirmation.

I would like to support 256 pages if possible, but I have other items
that need fixing before worrying about performance. :-)

Scott