SUNRPC: provide a mechanism for collecting stats in the RPC client

Add a simple mechanism for collecting stats in the RPC client.  Stats are
tabulated during xprt_release.  Note that per_cpu shenanigans are not
required here because the RPC client already serializes on the transport
write lock.

Test plan:
Compile kernel with CONFIG_NFS enabled.  Basic performance regression
testing with high-speed networking and high performance server.

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

3 files changed, 113 insertions, 3 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 84eb5b4565fc..0bb23e8e9d0c 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -28,12 +28,11 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/utsname.h>
+#include <linux/workqueue.h>
 
 #include <linux/sunrpc/clnt.h>
-#include <linux/workqueue.h>
 #include <linux/sunrpc/rpc_pipe_fs.h>
-
-#include <linux/nfs.h>
+#include <linux/sunrpc/metrics.h>
 
 
 #define RPC_SLACK_SPACE         (1024)  /* total overkill */
@@ -147,6 +146,7 @@ rpc_new_client(struct rpc_xprt *xprt, char *servname,
         clnt->cl_vers     = version->number;
         clnt->cl_prot     = xprt->prot;
         clnt->cl_stats    = program->stats;
+        clnt->cl_metrics  = rpc_alloc_iostats(clnt);
         rpc_init_wait_queue(&clnt->cl_pmap_default.pm_bindwait, "bindwait");
 
         if (!clnt->cl_port)
@@ -245,6 +245,7 @@ rpc_clone_client(struct rpc_clnt *clnt)
         if (new->cl_auth)
                 atomic_inc(&new->cl_auth->au_count);
         new->cl_pmap            = &new->cl_pmap_default;
+        new->cl_metrics         = rpc_alloc_iostats(clnt);
         rpc_init_wait_queue(&new->cl_pmap_default.pm_bindwait, "bindwait");
         return new;
 out_no_clnt:
@@ -315,6 +316,8 @@ rpc_destroy_client(struct rpc_clnt *clnt)
         if (clnt->cl_server != clnt->cl_inline_name)
                 kfree(clnt->cl_server);
 out_free:
+        rpc_free_iostats(clnt->cl_metrics);
+        clnt->cl_metrics = NULL;
         if (clnt->cl_dentry)
                 dput(clnt->cl_dentry);
         kfree(clnt);
diff --git a/net/sunrpc/stats.c b/net/sunrpc/stats.c
index 4979f226e285..24ac7163b9c7 100644
--- a/net/sunrpc/stats.c
+++ b/net/sunrpc/stats.c
@@ -21,6 +21,7 @@
 #include <linux/seq_file.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/svcsock.h>
+#include <linux/sunrpc/metrics.h>
 
 #define RPCDBG_FACILITY RPCDBG_MISC
 
@@ -106,6 +107,110 @@ void svc_seq_show(struct seq_file *seq, const struct svc_stat *statp) {
         }
 }
 
+/**
+ * rpc_alloc_iostats - allocate an rpc_iostats structure
+ * @clnt: RPC program, version, and xprt
+ *
+ */
+struct rpc_iostats *rpc_alloc_iostats(struct rpc_clnt *clnt)
+{
+        unsigned int ops = clnt->cl_maxproc;
+        size_t size = ops * sizeof(struct rpc_iostats);
+        struct rpc_iostats *new;
+
+        new = kmalloc(size, GFP_KERNEL);
+        if (new)
+                memset(new, 0 , size);
+        return new;
+}
+EXPORT_SYMBOL(rpc_alloc_iostats);
+
+/**
+ * rpc_free_iostats - release an rpc_iostats structure
+ * @stats: doomed rpc_iostats structure
+ *
+ */
+void rpc_free_iostats(struct rpc_iostats *stats)
+{
+        kfree(stats);
+}
+EXPORT_SYMBOL(rpc_free_iostats);
+
+/**
+ * rpc_count_iostats - tally up per-task stats
+ * @task: completed rpc_task
+ *
+ * Relies on the caller for serialization.
+ */
+void rpc_count_iostats(struct rpc_task *task)
+{
+        struct rpc_rqst *req = task->tk_rqstp;
+        struct rpc_iostats *stats = task->tk_client->cl_metrics;
+        struct rpc_iostats *op_metrics;
+        long rtt, execute, queue;
+
+        if (!stats || !req)
+                return;
+        op_metrics = &stats[task->tk_msg.rpc_proc->p_proc];
+
+        op_metrics->om_ops++;
+        op_metrics->om_ntrans += req->rq_ntrans;
+        op_metrics->om_timeouts += task->tk_timeouts;
+
+        op_metrics->om_bytes_sent += task->tk_bytes_sent;
+        op_metrics->om_bytes_recv += req->rq_received;
+
+        queue = (long)req->rq_xtime - task->tk_start;
+        if (queue < 0)
+                queue = -queue;
+        op_metrics->om_queue += queue;
+
+        rtt = task->tk_rtt;
+        if (rtt < 0)
+                rtt = -rtt;
+        op_metrics->om_rtt += rtt;
+
+        execute = (long)jiffies - task->tk_start;
+        if (execute < 0)
+                execute = -execute;
+        op_metrics->om_execute += execute;
+}
+
+#define MILLISECS_PER_JIFFY     (1000UL / HZ)
+
+void rpc_print_iostats(struct seq_file *seq, struct rpc_clnt *clnt)
+{
+        struct rpc_iostats *stats = clnt->cl_metrics;
+        struct rpc_xprt *xprt = clnt->cl_xprt;
+        unsigned int op, maxproc = clnt->cl_maxproc;
+
+        if (!stats)
+                return;
+
+        seq_printf(seq, "\tRPC iostats version: %s  ", RPC_IOSTATS_VERS);
+        seq_printf(seq, "p/v: %u/%u (%s)\n",
+                        clnt->cl_prog, clnt->cl_vers, clnt->cl_protname);
+
+        if (xprt)
+                xprt->ops->print_stats(xprt, seq);
+
+        seq_printf(seq, "\tper-op statistics\n");
+        for (op = 0; op < maxproc; op++) {
+                struct rpc_iostats *metrics = &stats[op];
+                seq_printf(seq, "%12u: ", op);
+                seq_printf(seq, "%lu %lu %lu %Lu %Lu %Lu %Lu %Lu\n",
+                                metrics->om_ops,
+                                metrics->om_ntrans,
+                                metrics->om_timeouts,
+                                metrics->om_bytes_sent,
+                                metrics->om_bytes_recv,
+                                metrics->om_queue * MILLISECS_PER_JIFFY,
+                                metrics->om_rtt * MILLISECS_PER_JIFFY,
+                                metrics->om_execute * MILLISECS_PER_JIFFY);
+        }
+}
+EXPORT_SYMBOL(rpc_print_iostats);
+
 /*
  * Register/unregister RPC proc files
  */
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index c6241976a6ee..eb5a262e024e 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -44,6 +44,7 @@
 #include <linux/random.h>
 
 #include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/metrics.h>
 
 /*
  * Local variables
@@ -859,6 +860,7 @@ void xprt_release(struct rpc_task *task)
 
         if (!(req = task->tk_rqstp))
                 return;
+        rpc_count_iostats(task);
         spin_lock_bh(&xprt->transport_lock);
         xprt->ops->release_xprt(xprt, task);
         if (xprt->ops->release_request)