> On Nov 3, 2015, at 3:10 PM, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
>
>
>> On Oct 16, 2015, at 9:30 AM, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
>>
>> 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 <chuck.lever@xxxxxxxxxx>
>> --
>
> Bruce, can you take this for 4.4 ?
Hi Bruce-
Your 4.4 pull request did not include this patch.
>> net/sunrpc/xprtrdma/svc_rdma_sendto.c | 7 +++++++
>> 1 files changed, 7 insertions(+), 0 deletions(-)
>>
>> 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,
>>
>> --
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>
> —
> Chuck Lever
>
>
>
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—
Chuck Lever
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