/*
* linux/fs/nfs/iostat.h
*
* Declarations for NFS client per-mount statistics
*
* Copyright (C) 2005, 2006 Chuck Lever <cel@netapp.com>
*
* NFS client per-mount statistics provide information about the health of
* the NFS client and the health of each NFS mount point. Generally these
* are not for detailed problem diagnosis, but simply to indicate that there
* is a problem.
*
* 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.
*/
#ifndef _NFS_IOSTAT
#define _NFS_IOSTAT
#define NFS_IOSTAT_VERS "1.0"
/*
* NFS byte counters
*
* 1. SERVER - the number of payload bytes read from or written to the
* server by the NFS client via an NFS READ or WRITE request.
*
* 2. NORMAL - the number of bytes read or written by applications via
* the read(2) and write(2) system call interfaces.
*
* 3. DIRECT - the number of bytes read or written from files opened
* with the O_DIRECT flag.
*
* These counters give a view of the data throughput into and out of the NFS
* client. Comparing the number of bytes requested by an application with the
* number of bytes the client requests from the server can provide an
* indication of client efficiency (per-op, cache hits, etc).
*
* These counters can also help characterize which access methods are in
* use. DIRECT by itself shows whether there is any O_DIRECT traffic.
* NORMAL + DIRECT shows how much data is going through the system call
* interface. A large amount of SERVER traffic without much NORMAL or
* DIRECT traffic shows that applications are using mapped files.
*
* NFS page counters
*
* These count the number of pages read or written via nfs_readpage(),
* nfs_readpages(), or their write equivalents.
*/
enum nfs_stat_bytecounters {
NFSIOS_NORMALREADBYTES = 0,
NFSIOS_NORMALWRITTENBYTES,
NFSIOS_DIRECTREADBYTES,
NFSIOS_DIRECTWRITTENBYTES,
NFSIOS_SERVERREADBYTES,
NFSIOS_SERVERWRITTENBYTES,
NFSIOS_READPAGES,
NFSIOS_WRITEPAGES,
__NFSIOS_BYTESMAX,
};
/*
* NFS event counters
*
* These counters provide a low-overhead way of monitoring client activity
* without enabling NFS trace debugging. The counters show the rate at
* which VFS requests are made, and how often the client invalidates its
* data and attribute caches. This allows system administrators to monitor
* such things as how close-to-open is working, and answer questions such
* as "why are there so many GETATTR requests on the wire?"
*
* They also count anamolous events such as short reads and writes, silly
* renames due to close-after-delete, and operations that change the size
* of a file (such operations can often be the source of data corruption
* if applications aren't using file locking properly).
*/
enum nfs_stat_eventcounters {
NFSIOS_INODEREVALIDATE = 0,
NFSIOS_DENTRYREVALIDATE,
NFSIOS_DATAINVALIDATE,
NFSIOS_ATTRINVALIDATE,
NFSIOS_VFSOPEN,
NFSIOS_VFSLOOKUP,
NFSIOS_VFSACCESS,
NFSIOS_VFSUPDATEPAGE,
NFSIOS_VFSREADPAGE,
NFSIOS_VFSREADPAGES,
NFSIOS_VFSWRITEPAGE,
NFSIOS_VFSWRITEPAGES,
NFSIOS_VFSGETDENTS,
NFSIOS_VFSSETATTR,
NFSIOS_VFSFLUSH,
NFSIOS_VFSFSYNC,
NFSIOS_VFSLOCK,
NFSIOS_VFSRELEASE,
NFSIOS_CONGESTIONWAIT,
NFSIOS_SETATTRTRUNC,
NFSIOS_EXTENDWRITE,
NFSIOS_SILLYRENAME,
NFSIOS_SHORTREAD,
NFSIOS_SHORTWRITE,
__NFSIOS_COUNTSMAX,
};
#ifdef __KERNEL__
#include <linux/percpu.h>
#include <linux/cache.h>
struct nfs_iostats {
unsigned long long bytes[__NFSIOS_BYTESMAX];
unsigned long events[__NFSIOS_COUNTSMAX];
} ____cacheline_aligned;
static inline void nfs_inc_stats(struct inode *inode, enum nfs_stat_eventcounters stat)
{
struct nfs_iostats *iostats;
int cpu;
cpu = get_cpu();
iostats = per_cpu_ptr(NFS_SERVER(inode)->io_stats, cpu);
iostats->events[stat] ++;
put_cpu_no_resched();
}
static inline void nfs_add_stats(struct inode *inode, enum nfs_stat_bytecounters stat, unsigned long addend)
{
struct nfs_iostats *iostats;
int cpu;
cpu = get_cpu();
iostats = per_cpu_ptr(NFS_SERVER(inode)->io_stats, cpu);
iostats->bytes[stat] += addend;
put_cpu_no_resched();
}
static inline struct nfs_iostats *nfs_alloc_iostats(void)
{
return alloc_percpu(struct nfs_iostats);
}
static inline void nfs_free_iostats(struct nfs_iostats *stats)
{
free_percpu(stats);
}
#endif
#endif
