At 01:29 PM 10/8/2008, Trond Myklebust wrote:
>On Wed, 2008-10-08 at 11:48 -0400, Tom Talpey wrote:
>> The RPC/RDMA protocol allows clients and servers to avoid RDMA
>> operations for data which is purely the result of XDR padding.
>> On the client, automatically insert the necessary padding for
>> such server replies, and optionally don't marshal such chunks.
>>
>> Signed-off-by: Tom Talpey <talpey@xxxxxxxxxx>
>> ---
>>
>> net/sunrpc/xprtrdma/rpc_rdma.c | 22 ++++++++++++++++++++--
>> net/sunrpc/xprtrdma/transport.c | 9 +++++++++
>> 2 files changed, 29 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
>> index 721dae7..c4b8011 100644
>> --- a/net/sunrpc/xprtrdma/rpc_rdma.c
>> +++ b/net/sunrpc/xprtrdma/rpc_rdma.c
>> @@ -118,6 +118,11 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf,
>unsigned int pos,
>> }
>>
>> if (xdrbuf->tail[0].iov_len) {
>> + /* the rpcrdma protocol allows us to omit any trailing
>> + * xdr pad bytes, saving the server an RDMA operation. */
>> + extern int xprt_rdma_pad_optimize; /* 0 == old server compat */
> ^^^^^^^^^^^^^^^^^^^
>Globals should really be declared in a header file. 'sparse' will
>complain if you don't...
Nope, sparse was silent. I did get a lot of noise from some __cold__ attributes
in global header files (at least doing make C=1), that's it.
I'll move the extern.
Tom.
>
>> + if (xdrbuf->tail[0].iov_len < 4 && xprt_rdma_pad_optimize)
>> + return n;
>> if (n == nsegs)
>> return 0;
>> seg[n].mr_page = NULL;
>> @@ -594,7 +599,7 @@ rpcrdma_count_chunks(struct rpcrdma_rep *rep,
>unsigned int max, int wrchunk, __b
>> * Scatter inline received data back into provided iov's.
>> */
>> static void
>> -rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len)
>> +rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int
>copy_len, int pad)
>> {
>> int i, npages, curlen, olen;
>> char *destp;
>> @@ -660,6 +665,13 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst,
>char *srcp, int copy_len)
>> } else
>> rqst->rq_rcv_buf.tail[0].iov_len = 0;
>>
>> + if (pad) {
>> + /* implicit padding on terminal chunk */
>> + unsigned char *p = rqst->rq_rcv_buf.tail[0].iov_base;
>> + while (pad--)
>> + p[rqst->rq_rcv_buf.tail[0].iov_len++] = 0;
>> + }
>> +
>> if (copy_len)
>> dprintk("RPC: %s: %d bytes in"
>> " %d extra segments (%d lost)\n",
>> @@ -794,14 +806,20 @@ repost:
>> ((unsigned char *)iptr - (unsigned char *)headerp);
>> status = rep->rr_len + rdmalen;
>> r_xprt->rx_stats.total_rdma_reply += rdmalen;
>> + /* special case - last chunk may omit padding */
>> + if (rdmalen &= 3) {
>> + rdmalen = 4 - rdmalen;
>> + status += rdmalen;
>> + }
>> } else {
>> /* else ordinary inline */
>> + rdmalen = 0;
>> iptr = (__be32 *)((unsigned char *)headerp + 28);
>> rep->rr_len -= 28; /*sizeof *headerp;*/
>> status = rep->rr_len;
>> }
>> /* Fix up the rpc results for upper layer */
>> - rpcrdma_inline_fixup(rqst, (char *)iptr, rep->rr_len);
>> + rpcrdma_inline_fixup(rqst, (char *)iptr, rep->rr_len, rdmalen);
>> break;
>>
>> case __constant_htonl(RDMA_NOMSG):
>> diff --git a/net/sunrpc/xprtrdma/transport.c
>b/net/sunrpc/xprtrdma/transport.c
>> index ec6d1e7..c7d2380 100644
>> --- a/net/sunrpc/xprtrdma/transport.c
>> +++ b/net/sunrpc/xprtrdma/transport.c
>> @@ -71,6 +71,7 @@ static unsigned int xprt_rdma_max_inline_read =
>RPCRDMA_DEF_INLINE;
>> static unsigned int xprt_rdma_max_inline_write = RPCRDMA_DEF_INLINE;
>> static unsigned int xprt_rdma_inline_write_padding;
>> static unsigned int xprt_rdma_memreg_strategy = RPCRDMA_FRMR;
>> + int xprt_rdma_pad_optimize = 0;
>>
>> #ifdef RPC_DEBUG
>>
>> @@ -136,6 +137,14 @@ static ctl_table xr_tunables_table[] = {
>> .extra2 = &max_memreg,
>> },
>> {
>> + .ctl_name = CTL_UNNUMBERED,
>> + .procname = "rdma_pad_optimize",
>> + .data = &xprt_rdma_pad_optimize,
>> + .maxlen = sizeof(unsigned int),
>> + .mode = 0644,
>> + .proc_handler = &proc_dointvec,
>> + },
>> + {
>> .ctl_name = 0,
>> },
>> };
>>
>> --
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