2015-11-12 14:47:23

by Chuck Lever III

[permalink] [raw]
Subject: Fwd: [PATCH] svcrdma: Do not send XDR roundup bytes for a write chunk

I wish git send-mail had an address book. I’m really tired
of misspelling the to/cc addresses on patches.

Resending so there is one thread for all replies. Apologies
for the noise.


> Begin forwarded message:
>
> From: Chuck Lever <[email protected]>
> Subject: [PATCH] svcrdma: Do not send XDR roundup bytes for a write chunk
> Date: November 12, 2015 at 9:44:33 AM EST
> To: [email protected]
> Cc: [email protected], [email protected]
>
> Minor optimization: when dealing with write chunk XDR roundup, do
> not post a Write WR for the zero bytes in the pad. Simply update
> the write segment in the RPC-over-RDMA header to reflect the extra
> pad bytes.
>
> The Reply chunk is also a write chunk, but the server does not use
> send_write_chunks() to send the Reply chunk. That's OK in this case:
> the server Upper Layer typically marshals the Reply chunk contents
> in a single contiguous buffer, without a separate tail for the XDR
> pad.
>
> The comments and the variable naming refer to "chunks" but what is
> really meant is "segments." The existing code sends only one
> xdr_write_chunk per RPC reply.
>
> The fix assumes this as well. When the XDR pad in the first write
> chunk is reached, the assumption is the Write list is complete and
> send_write_chunks() returns.
>
> That will remain a valid assumption until the server Upper Layer can
> support multiple bulk payload results per RPC.
>
> Signed-off-by: Chuck Lever <[email protected]>
> ---
> net/sunrpc/xprtrdma/svc_rdma_sendto.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> index 1dfae83..6c48901 100644
> --- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> @@ -342,6 +342,13 @@ static int send_write_chunks(struct svcxprt_rdma *xprt,
> arg_ch->rs_handle,
> arg_ch->rs_offset,
> write_len);
> +
> + /* Do not send XDR pad bytes */
> + if (chunk_no && write_len < 4) {
> + chunk_no++;
> + break;
> + }
> +
> chunk_off = 0;
> while (write_len) {
> ret = send_write(xprt, rqstp,
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html

--
Chuck Lever






2015-11-12 15:17:25

by J. Bruce Fields

[permalink] [raw]
Subject: Re: Fwd: [PATCH] svcrdma: Do not send XDR roundup bytes for a write chunk

On Thu, Nov 12, 2015 at 09:47:13AM -0500, Chuck Lever wrote:
> I wish git send-mail had an address book. I’m really tired
> of misspelling the to/cc addresses on patches.

Hah. Yeah, my hack is a text file of addresses that I cut-and-paste
from.

--b.

>
> Resending so there is one thread for all replies. Apologies
> for the noise.
>
>
> > Begin forwarded message:
> >
> > From: Chuck Lever <[email protected]>
> > Subject: [PATCH] svcrdma: Do not send XDR roundup bytes for a write chunk
> > Date: November 12, 2015 at 9:44:33 AM EST
> > To: [email protected]
> > Cc: [email protected], [email protected]
> >
> > Minor optimization: when dealing with write chunk XDR roundup, do
> > not post a Write WR for the zero bytes in the pad. Simply update
> > the write segment in the RPC-over-RDMA header to reflect the extra
> > pad bytes.
> >
> > The Reply chunk is also a write chunk, but the server does not use
> > send_write_chunks() to send the Reply chunk. That's OK in this case:
> > the server Upper Layer typically marshals the Reply chunk contents
> > in a single contiguous buffer, without a separate tail for the XDR
> > pad.
> >
> > The comments and the variable naming refer to "chunks" but what is
> > really meant is "segments." The existing code sends only one
> > xdr_write_chunk per RPC reply.
> >
> > The fix assumes this as well. When the XDR pad in the first write
> > chunk is reached, the assumption is the Write list is complete and
> > send_write_chunks() returns.
> >
> > That will remain a valid assumption until the server Upper Layer can
> > support multiple bulk payload results per RPC.
> >
> > Signed-off-by: Chuck Lever <[email protected]>
> > ---
> > net/sunrpc/xprtrdma/svc_rdma_sendto.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> > index 1dfae83..6c48901 100644
> > --- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> > +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> > @@ -342,6 +342,13 @@ static int send_write_chunks(struct svcxprt_rdma *xprt,
> > arg_ch->rs_handle,
> > arg_ch->rs_offset,
> > write_len);
> > +
> > + /* Do not send XDR pad bytes */
> > + if (chunk_no && write_len < 4) {
> > + chunk_no++;
> > + break;
> > + }
> > +
> > chunk_off = 0;
> > while (write_len) {
> > ret = send_write(xprt, rqstp,
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> > the body of a message to [email protected]
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>
> --
> Chuck Lever
>
>
>

2015-11-12 18:30:43

by Jason Gunthorpe

[permalink] [raw]
Subject: Re: Fwd: [PATCH] svcrdma: Do not send XDR roundup bytes for a write chunk

On Thu, Nov 12, 2015 at 09:47:13AM -0500, Chuck Lever wrote:
> I wish git send-mail had an address book. I’m really tired
> of misspelling the to/cc addresses on patches.

It does:

CONFIGURATION
sendemail.aliasesfile
To avoid typing long email addresses, point this to one or more email aliases files. You must also supply
sendemail.aliasfiletype.

sendemail.aliasfiletype
Format of the file(s) specified in sendemail.aliasesfile. Must be one of mutt, mailrc, pine, elm, or gnus.

Jason