> On Jan 24, 2017, at 2:12 PM, Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> wrote:
>
> Hi Chuck,
>
> On 01/23/2017 03:52 PM, Chuck Lever wrote:
>> Pad optimization is changed by echoing into
>> /proc/sys/sunrpc/rdma_pad_optimize. This is a global setting,
>> affecting all RPC-over-RDMA connections to all servers.
>>
>> The marshaling code picks up that value and uses it for decisions
>> about how to construct each RPC-over-RDMA frame. Having it change
>> suddenly in mid-operation can result in unexpected failures. And
>> some servers a client mounts might need chunk round-up, while
>> others don't.
>>
>> So instead, copy the pad_optimize setting into each connection's
>> rpcrdma_ia when the transport is created, and use the copy, which
>> can't change during the life of the connection, instead.
>
> Does the rdma_pad_optimize option have documentation somewhere that needs to be updated to describe the new behavior?
I'm not aware of any. No documentation was changed by d5440e27d3e5.
> Anna
>
>>
>> This also removes a hack: rpcrdma_convert_iovs was using
>> the remote-invalidation-expected flag to predict when it could leave
>> out Write chunk padding. This is because the Linux server handles
>> implicit XDR padding on Write chunks correctly, and only Linux
>> servers can set the connection's remote-invalidation-expected flag.
>>
>> It's more sensible to use the pad optimization setting instead.
>>
>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>> ---
>> net/sunrpc/xprtrdma/rpc_rdma.c | 28 ++++++++++++++--------------
>> net/sunrpc/xprtrdma/verbs.c | 1 +
>> net/sunrpc/xprtrdma/xprt_rdma.h | 1 +
>> 3 files changed, 16 insertions(+), 14 deletions(-)
>>
>> diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
>> index a524d3c..c634f0f 100644
>> --- a/net/sunrpc/xprtrdma/rpc_rdma.c
>> +++ b/net/sunrpc/xprtrdma/rpc_rdma.c
>> @@ -186,9 +186,9 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
>> */
>>
>> static int
>> -rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
>> - enum rpcrdma_chunktype type, struct rpcrdma_mr_seg *seg,
>> - bool reminv_expected)
>> +rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
>> + unsigned int pos, enum rpcrdma_chunktype type,
>> + struct rpcrdma_mr_seg *seg)
>> {
>> int len, n, p, page_base;
>> struct page **ppages;
>> @@ -229,14 +229,15 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
>> /* When encoding a Read chunk, the tail iovec contains an
>> * XDR pad and may be omitted.
>> */
>> - if (type == rpcrdma_readch && xprt_rdma_pad_optimize)
>> + if (type == rpcrdma_readch && r_xprt->rx_ia.ri_implicit_roundup)
>> return n;
>>
>> - /* When encoding the Write list, some servers need to see an extra
>> - * segment for odd-length Write chunks. The upper layer provides
>> - * space in the tail iovec for this purpose.
>> + /* When encoding a Write chunk, some servers need to see an
>> + * extra segment for non-XDR-aligned Write chunks. The upper
>> + * layer provides space in the tail iovec that may be used
>> + * for this purpose.
>> */
>> - if (type == rpcrdma_writech && reminv_expected)
>> + if (type == rpcrdma_writech && r_xprt->rx_ia.ri_implicit_roundup)
>> return n;
>>
>> if (xdrbuf->tail[0].iov_len) {
>> @@ -291,7 +292,8 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
>> if (rtype == rpcrdma_areadch)
>> pos = 0;
>> seg = req->rl_segments;
>> - nsegs = rpcrdma_convert_iovs(&rqst->rq_snd_buf, pos, rtype, seg, false);
>> + nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_snd_buf, pos,
>> + rtype, seg);
>> if (nsegs < 0)
>> return ERR_PTR(nsegs);
>>
>> @@ -353,10 +355,9 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
>> }
>>
>> seg = req->rl_segments;
>> - nsegs = rpcrdma_convert_iovs(&rqst->rq_rcv_buf,
>> + nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf,
>> rqst->rq_rcv_buf.head[0].iov_len,
>> - wtype, seg,
>> - r_xprt->rx_ia.ri_reminv_expected);
>> + wtype, seg);
>> if (nsegs < 0)
>> return ERR_PTR(nsegs);
>>
>> @@ -421,8 +422,7 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
>> }
>>
>> seg = req->rl_segments;
>> - nsegs = rpcrdma_convert_iovs(&rqst->rq_rcv_buf, 0, wtype, seg,
>> - r_xprt->rx_ia.ri_reminv_expected);
>> + nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf, 0, wtype, seg);
>> if (nsegs < 0)
>> return ERR_PTR(nsegs);
>>
>> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
>> index 11d0774..2a6a367 100644
>> --- a/net/sunrpc/xprtrdma/verbs.c
>> +++ b/net/sunrpc/xprtrdma/verbs.c
>> @@ -208,6 +208,7 @@
>>
>> /* Default settings for RPC-over-RDMA Version One */
>> r_xprt->rx_ia.ri_reminv_expected = false;
>> + r_xprt->rx_ia.ri_implicit_roundup = xprt_rdma_pad_optimize;
>> rsize = RPCRDMA_V1_DEF_INLINE_SIZE;
>> wsize = RPCRDMA_V1_DEF_INLINE_SIZE;
>>
>> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
>> index e35efd4..c137154 100644
>> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
>> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
>> @@ -75,6 +75,7 @@ struct rpcrdma_ia {
>> unsigned int ri_max_inline_write;
>> unsigned int ri_max_inline_read;
>> bool ri_reminv_expected;
>> + bool ri_implicit_roundup;
>> enum ib_mr_type ri_mrtype;
>> struct ib_qp_attr ri_qp_attr;
>> struct ib_qp_init_attr ri_qp_init_attr;
>>
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--
Chuck Lever
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