SUNRPC: switchable buffer allocation

 Add RPC client transport switch support for replacing buffer management
 on a per-transport basis.

 In the current IPv4 socket transport implementation, RPC buffers are
 allocated as needed for each RPC message that is sent.  Some transport
 implementations may choose to use pre-allocated buffers for encoding,
 sending, receiving, and unmarshalling RPC messages, however.  For
 transports capable of direct data placement, the buffers can be carved
 out of a pre-registered area of memory rather than from a slab cache.

 Test-plan:
 Millions of fsx operations.  Performance characterization with "sio" and
 "iozone".  Use oprofile and other tools to look for significant regression
 in CPU utilization.

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 8 insertions, 6 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index b23c0d328c9c..25cba94c5683 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -644,24 +644,26 @@ call_reserveresult(struct rpc_task *task)
 
 /*
  * 2.   Allocate the buffer. For details, see sched.c:rpc_malloc.
- *      (Note: buffer memory is freed in rpc_task_release).
+ *      (Note: buffer memory is freed in xprt_release).
  */
 static void
 call_allocate(struct rpc_task *task)
 {
+        struct rpc_rqst *req = task->tk_rqstp;
+        struct rpc_xprt *xprt = task->tk_xprt;
         unsigned int    bufsiz;
 
         dprintk("RPC: %4d call_allocate (status %d)\n", 
                                 task->tk_pid, task->tk_status);
         task->tk_action = call_bind;
-        if (task->tk_buffer)
+        if (req->rq_buffer)
                 return;
 
         /* FIXME: compute buffer requirements more exactly using
          * auth->au_wslack */
         bufsiz = task->tk_msg.rpc_proc->p_bufsiz + RPC_SLACK_SPACE;
 
-        if (rpc_malloc(task, bufsiz << 1) != NULL)
+        if (xprt->ops->buf_alloc(task, bufsiz << 1) != NULL)
                 return;
         printk(KERN_INFO "RPC: buffer allocation failed for task %p\n", task); 
 
@@ -704,14 +706,14 @@ call_encode(struct rpc_task *task)
                                 task->tk_pid, task->tk_status);
 
         /* Default buffer setup */
-        bufsiz = task->tk_bufsize >> 1;
-        sndbuf->head[0].iov_base = (void *)task->tk_buffer;
+        bufsiz = req->rq_bufsize >> 1;
+        sndbuf->head[0].iov_base = (void *)req->rq_buffer;
         sndbuf->head[0].iov_len  = bufsiz;
         sndbuf->tail[0].iov_len  = 0;
         sndbuf->page_len         = 0;
         sndbuf->len              = 0;
         sndbuf->buflen           = bufsiz;
-        rcvbuf->head[0].iov_base = (void *)((char *)task->tk_buffer + bufsiz);
+        rcvbuf->head[0].iov_base = (void *)((char *)req->rq_buffer + bufsiz);
         rcvbuf->head[0].iov_len  = bufsiz;
         rcvbuf->tail[0].iov_len  = 0;
         rcvbuf->page_len         = 0;