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+/*
+ * User-space visible declarations for NFS client per-mount
+ * point 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 _LINUX_NFS_IOSTAT
+#define _LINUX_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.
+ *
+ * NB: When adding new byte counters, please include the measured
+ * units in the name of each byte counter to help users of this
+ * interface determine what exactly is being counted.
+ */
+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_DELAY,
+ __NFSIOS_COUNTSMAX,
+};
+
+#endif /* _LINUX_NFS_IOSTAT */