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>
diff --git a/include/linux/sunrpc/metrics.h b/include/linux/sunrpc/metrics.h
new file mode 100644
index 0000000..8f96e9d
--- /dev/null
+++ b/include/linux/sunrpc/metrics.h
@@ -0,0 +1,77 @@
+/*
+ * linux/include/linux/sunrpc/metrics.h
+ *
+ * Declarations for RPC client per-operation metrics
+ *
+ * Copyright (C) 2005 Chuck Lever <cel@netapp.com>
+ *
+ * RPC client per-operation statistics provide latency and retry
+ * information about each type of RPC procedure in a given RPC program.
+ * These statistics are not for detailed problem diagnosis, but simply
+ * to indicate whether the problem is local or remote.
+ *
+ * These counters are not meant to be human-readable, but are meant to be
+ * integrated into system monitoring tools such as "sar" and "iostat". As
+ * such, the counters are sampled by the tools over time, and are never
+ * zeroed after a file system is mounted. Moving averages can be computed
+ * by the tools by taking the difference between two instantaneous samples
+ * and dividing that by the time between the samples.
+ *
+ * The counters are maintained in a single array per RPC client, indexed
+ * by procedure number. There is no need to maintain separate counter
+ * arrays per-CPU because these counters are always modified behind locks.
+ */
+
+#ifndef _LINUX_SUNRPC_METRICS_H
+#define _LINUX_SUNRPC_METRICS_H
+
+#include <linux/seq_file.h>
+
+#define RPC_IOSTATS_VERS "1.0"
+
+struct rpc_iostats {
+ /*
+ * These counters give an idea about how many request
+ * transmissions are required, on average, to complete that
+ * particular procedure. Some procedures may require more
+ * than one transmission because the server is unresponsive,
+ * the client is retransmitting too aggressively, or the
+ * requests are large and the network is congested.
+ */
+ unsigned long om_ops, /* count of operations */
+ om_ntrans, /* count of RPC transmissions */
+ om_timeouts; /* count of major timeouts */
+
+ /*
+ * These count how many bytes are sent and received for a
+ * given RPC procedure type. This indicates how much load a
+ * particular procedure is putting on the network. These
+ * counts include the RPC and ULP headers, and the request
+ * payload.
+ */
+ unsigned long long om_bytes_sent, /* count of bytes out */
+ om_bytes_recv; /* count of bytes in */
+
+ /*
+ * The length of time an RPC request waits in queue before
+ * transmission, the network + server latency of the request,
+ * and the total time the request spent from init to release
+ * are measured.
+ */
+ unsigned long long om_queue, /* jiffies queued for xmit */
+ om_rtt, /* jiffies for RPC RTT */
+ om_execute; /* jiffies for RPC execution */
+} ____cacheline_aligned;
+
+struct rpc_task;
+struct rpc_clnt;
+
+/*
+ * EXPORTed functions for managing rpc_iostats structures
+ */
+struct rpc_iostats * rpc_alloc_iostats(struct rpc_clnt *);
+void rpc_count_iostats(struct rpc_task *);
+void rpc_print_iostats(struct seq_file *, struct rpc_clnt *);
+void rpc_free_iostats(struct rpc_iostats *);
+
+#endif /* _LINUX_SUNRPC_METRICS_H */