From 68778945e46f143ed7974b427a8065f69a4ce944 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 15 Sep 2016 10:55:37 -0400 Subject: SUNRPC: Separate buffer pointers for RPC Call and Reply messages For xprtrdma, the RPC Call and Reply buffers are involved in real I/O operations. To start with, the DMA direction of the I/O for a Call is opposite that of a Reply. In the current arrangement, the Reply buffer address is on a four-byte alignment just past the call buffer. Would be friendlier on some platforms if that was at a DMA cache alignment instead. Because the current arrangement allocates a single memory region which contains both buffers, the RPC Reply buffer often contains a page boundary in it when the Call buffer is large enough (which is frequent). It would be a little nicer for setting up DMA operations (and possible registration of the Reply buffer) if the two buffers were separated, well-aligned, and contained as few page boundaries as possible. Now, I could just pad out the single memory region used for the pair of buffers. But frequently that would mean a lot of unused space to ensure the Reply buffer did not have a page boundary. Add a separate pointer to rpc_rqst that points right to the RPC Reply buffer. This makes no difference to xprtsock, but it will help xprtrdma in subsequent patches. Signed-off-by: Chuck Lever Signed-off-by: Anna Schumaker --- net/sunrpc/clnt.c | 2 +- net/sunrpc/sched.c | 1 + net/sunrpc/xprtrdma/transport.c | 1 + 3 files changed, 3 insertions(+), 1 deletion(-) (limited to 'net') diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 5499fda0c1f3..34dd7b26ee5f 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -1766,7 +1766,7 @@ rpc_xdr_encode(struct rpc_task *task) req->rq_buffer, req->rq_callsize); xdr_buf_init(&req->rq_rcv_buf, - (char *)req->rq_buffer + req->rq_callsize, + req->rq_rbuffer, req->rq_rcvsize); p = rpc_encode_header(task); diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 6690ebc774ed..5db68b371db2 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -891,6 +891,7 @@ int rpc_malloc(struct rpc_task *task) dprintk("RPC: %5u allocated buffer of size %zu at %p\n", task->tk_pid, size, buf); rqst->rq_buffer = buf->data; + rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize; return 0; } EXPORT_SYMBOL_GPL(rpc_malloc); diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c index ebf14ba437c6..136caf3dd299 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -524,6 +524,7 @@ out: dprintk("RPC: %s: size %zd, request 0x%p\n", __func__, size, req); req->rl_connect_cookie = 0; /* our reserved value */ rqst->rq_buffer = req->rl_sendbuf->rg_base; + rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_rcvsize; return 0; out_rdmabuf: -- cgit v1.2.1