metrics.h

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/*
 *  linux/include/linux/sunrpc/metrics.h
 *
 *  Declarations for RPC client per-operation metrics
 *
 *  Copyright (C) 2005  Chuck Lever <[email protected]>
 *
 *  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>
#include <linux/ktime.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.
     */
    ktime_t         om_queue,   /* queued for xmit */
                om_rtt,     /* RPC RTT */
                om_execute; /* RPC execution */
} ____cacheline_aligned;

struct rpc_task;
struct rpc_clnt;

/*
 * EXPORTed functions for managing rpc_iostats structures
 */

#ifdef CONFIG_PROC_FS

struct rpc_iostats *    rpc_alloc_iostats(struct rpc_clnt *);
void            rpc_count_iostats(const struct rpc_task *,
                      struct rpc_iostats *);
void            rpc_print_iostats(struct seq_file *, struct rpc_clnt *);
void            rpc_free_iostats(struct rpc_iostats *);

#else  /*  CONFIG_PROC_FS  */

static inline struct rpc_iostats *rpc_alloc_iostats(struct rpc_clnt *clnt) { return NULL; }
static inline void rpc_count_iostats(const struct rpc_task *task,
                     struct rpc_iostats *stats) {}
static inline void rpc_print_iostats(struct seq_file *seq, struct rpc_clnt *clnt) {}
static inline void rpc_free_iostats(struct rpc_iostats *stats) {}

#endif  /*  CONFIG_PROC_FS  */

#endif /* _LINUX_SUNRPC_METRICS_H */