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-rw-r--r--Documentation/filesystems/knfsd-stats.txt159
-rw-r--r--Documentation/filesystems/nfs41-server.txt161
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1
2Kernel NFS Server Statistics
3============================
4
5This document describes the format and semantics of the statistics
6which the kernel NFS server makes available to userspace. These
7statistics are available in several text form pseudo files, each of
8which is described separately below.
9
10In most cases you don't need to know these formats, as the nfsstat(8)
11program from the nfs-utils distribution provides a helpful command-line
12interface for extracting and printing them.
13
14All the files described here are formatted as a sequence of text lines,
15separated by newline '\n' characters. Lines beginning with a hash
16'#' character are comments intended for humans and should be ignored
17by parsing routines. All other lines contain a sequence of fields
18separated by whitespace.
19
20/proc/fs/nfsd/pool_stats
21------------------------
22
23This file is available in kernels from 2.6.30 onwards, if the
24/proc/fs/nfsd filesystem is mounted (it almost always should be).
25
26The first line is a comment which describes the fields present in
27all the other lines. The other lines present the following data as
28a sequence of unsigned decimal numeric fields. One line is shown
29for each NFS thread pool.
30
31All counters are 64 bits wide and wrap naturally. There is no way
32to zero these counters, instead applications should do their own
33rate conversion.
34
35pool
36 The id number of the NFS thread pool to which this line applies.
37 This number does not change.
38
39 Thread pool ids are a contiguous set of small integers starting
40 at zero. The maximum value depends on the thread pool mode, but
41 currently cannot be larger than the number of CPUs in the system.
42 Note that in the default case there will be a single thread pool
43 which contains all the nfsd threads and all the CPUs in the system,
44 and thus this file will have a single line with a pool id of "0".
45
46packets-arrived
47 Counts how many NFS packets have arrived. More precisely, this
48 is the number of times that the network stack has notified the
49 sunrpc server layer that new data may be available on a transport
50 (e.g. an NFS or UDP socket or an NFS/RDMA endpoint).
51
52 Depending on the NFS workload patterns and various network stack
53 effects (such as Large Receive Offload) which can combine packets
54 on the wire, this may be either more or less than the number
55 of NFS calls received (which statistic is available elsewhere).
56 However this is a more accurate and less workload-dependent measure
57 of how much CPU load is being placed on the sunrpc server layer
58 due to NFS network traffic.
59
60sockets-enqueued
61 Counts how many times an NFS transport is enqueued to wait for
62 an nfsd thread to service it, i.e. no nfsd thread was considered
63 available.
64
65 The circumstance this statistic tracks indicates that there was NFS
66 network-facing work to be done but it couldn't be done immediately,
67 thus introducing a small delay in servicing NFS calls. The ideal
68 rate of change for this counter is zero; significantly non-zero
69 values may indicate a performance limitation.
70
71 This can happen either because there are too few nfsd threads in the
72 thread pool for the NFS workload (the workload is thread-limited),
73 or because the NFS workload needs more CPU time than is available in
74 the thread pool (the workload is CPU-limited). In the former case,
75 configuring more nfsd threads will probably improve the performance
76 of the NFS workload. In the latter case, the sunrpc server layer is
77 already choosing not to wake idle nfsd threads because there are too
78 many nfsd threads which want to run but cannot, so configuring more
79 nfsd threads will make no difference whatsoever. The overloads-avoided
80 statistic (see below) can be used to distinguish these cases.
81
82threads-woken
83 Counts how many times an idle nfsd thread is woken to try to
84 receive some data from an NFS transport.
85
86 This statistic tracks the circumstance where incoming
87 network-facing NFS work is being handled quickly, which is a good
88 thing. The ideal rate of change for this counter will be close
89 to but less than the rate of change of the packets-arrived counter.
90
91overloads-avoided
92 Counts how many times the sunrpc server layer chose not to wake an
93 nfsd thread, despite the presence of idle nfsd threads, because
94 too many nfsd threads had been recently woken but could not get
95 enough CPU time to actually run.
96
97 This statistic counts a circumstance where the sunrpc layer
98 heuristically avoids overloading the CPU scheduler with too many
99 runnable nfsd threads. The ideal rate of change for this counter
100 is zero. Significant non-zero values indicate that the workload
101 is CPU limited. Usually this is associated with heavy CPU usage
102 on all the CPUs in the nfsd thread pool.
103
104 If a sustained large overloads-avoided rate is detected on a pool,
105 the top(1) utility should be used to check for the following
106 pattern of CPU usage on all the CPUs associated with the given
107 nfsd thread pool.
108
109 - %us ~= 0 (as you're *NOT* running applications on your NFS server)
110
111 - %wa ~= 0
112
113 - %id ~= 0
114
115 - %sy + %hi + %si ~= 100
116
117 If this pattern is seen, configuring more nfsd threads will *not*
118 improve the performance of the workload. If this patten is not
119 seen, then something more subtle is wrong.
120
121threads-timedout
122 Counts how many times an nfsd thread triggered an idle timeout,
123 i.e. was not woken to handle any incoming network packets for
124 some time.
125
126 This statistic counts a circumstance where there are more nfsd
127 threads configured than can be used by the NFS workload. This is
128 a clue that the number of nfsd threads can be reduced without
129 affecting performance. Unfortunately, it's only a clue and not
130 a strong indication, for a couple of reasons:
131
132 - Currently the rate at which the counter is incremented is quite
133 slow; the idle timeout is 60 minutes. Unless the NFS workload
134 remains constant for hours at a time, this counter is unlikely
135 to be providing information that is still useful.
136
137 - It is usually a wise policy to provide some slack,
138 i.e. configure a few more nfsds than are currently needed,
139 to allow for future spikes in load.
140
141
142Note that incoming packets on NFS transports will be dealt with in
143one of three ways. An nfsd thread can be woken (threads-woken counts
144this case), or the transport can be enqueued for later attention
145(sockets-enqueued counts this case), or the packet can be temporarily
146deferred because the transport is currently being used by an nfsd
147thread. This last case is not very interesting and is not explicitly
148counted, but can be inferred from the other counters thus:
149
150packets-deferred = packets-arrived - ( sockets-enqueued + threads-woken )
151
152
153More
154----
155Descriptions of the other statistics file should go here.
156
157
158Greg Banks <gnb@sgi.com>
15926 Mar 2009
diff --git a/Documentation/filesystems/nfs41-server.txt b/Documentation/filesystems/nfs41-server.txt
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1NFSv4.1 Server Implementation
2
3Server support for minorversion 1 can be controlled using the
4/proc/fs/nfsd/versions control file. The string output returned
5by reading this file will contain either "+4.1" or "-4.1"
6correspondingly.
7
8Currently, server support for minorversion 1 is disabled by default.
9It can be enabled at run time by writing the string "+4.1" to
10the /proc/fs/nfsd/versions control file. Note that to write this
11control file, the nfsd service must be taken down. Use your user-mode
12nfs-utils to set this up; see rpc.nfsd(8)
13
14The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
15on the latest NFSv4.1 Internet Draft:
16http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-29
17
18From the many new features in NFSv4.1 the current implementation
19focuses on the mandatory-to-implement NFSv4.1 Sessions, providing
20"exactly once" semantics and better control and throttling of the
21resources allocated for each client.
22
23Other NFSv4.1 features, Parallel NFS operations in particular,
24are still under development out of tree.
25See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design
26for more information.
27
28The table below, taken from the NFSv4.1 document, lists
29the operations that are mandatory to implement (REQ), optional
30(OPT), and NFSv4.0 operations that are required not to implement (MNI)
31in minor version 1. The first column indicates the operations that
32are not supported yet by the linux server implementation.
33
34The OPTIONAL features identified and their abbreviations are as follows:
35 pNFS Parallel NFS
36 FDELG File Delegations
37 DDELG Directory Delegations
38
39The following abbreviations indicate the linux server implementation status.
40 I Implemented NFSv4.1 operations.
41 NS Not Supported.
42 NS* unimplemented optional feature.
43 P pNFS features implemented out of tree.
44 PNS pNFS features that are not supported yet (out of tree).
45
46Operations
47
48 +----------------------+------------+--------------+----------------+
49 | Operation | REQ, REC, | Feature | Definition |
50 | | OPT, or | (REQ, REC, | |
51 | | MNI | or OPT) | |
52 +----------------------+------------+--------------+----------------+
53 | ACCESS | REQ | | Section 18.1 |
54NS | BACKCHANNEL_CTL | REQ | | Section 18.33 |
55NS | BIND_CONN_TO_SESSION | REQ | | Section 18.34 |
56 | CLOSE | REQ | | Section 18.2 |
57 | COMMIT | REQ | | Section 18.3 |
58 | CREATE | REQ | | Section 18.4 |
59I | CREATE_SESSION | REQ | | Section 18.36 |
60NS*| DELEGPURGE | OPT | FDELG (REQ) | Section 18.5 |
61 | DELEGRETURN | OPT | FDELG, | Section 18.6 |
62 | | | DDELG, pNFS | |
63 | | | (REQ) | |
64NS | DESTROY_CLIENTID | REQ | | Section 18.50 |
65I | DESTROY_SESSION | REQ | | Section 18.37 |
66I | EXCHANGE_ID | REQ | | Section 18.35 |
67NS | FREE_STATEID | REQ | | Section 18.38 |
68 | GETATTR | REQ | | Section 18.7 |
69P | GETDEVICEINFO | OPT | pNFS (REQ) | Section 18.40 |
70P | GETDEVICELIST | OPT | pNFS (OPT) | Section 18.41 |
71 | GETFH | REQ | | Section 18.8 |
72NS*| GET_DIR_DELEGATION | OPT | DDELG (REQ) | Section 18.39 |
73P | LAYOUTCOMMIT | OPT | pNFS (REQ) | Section 18.42 |
74P | LAYOUTGET | OPT | pNFS (REQ) | Section 18.43 |
75P | LAYOUTRETURN | OPT | pNFS (REQ) | Section 18.44 |
76 | LINK | OPT | | Section 18.9 |
77 | LOCK | REQ | | Section 18.10 |
78 | LOCKT | REQ | | Section 18.11 |
79 | LOCKU | REQ | | Section 18.12 |
80 | LOOKUP | REQ | | Section 18.13 |
81 | LOOKUPP | REQ | | Section 18.14 |
82 | NVERIFY | REQ | | Section 18.15 |
83 | OPEN | REQ | | Section 18.16 |
84NS*| OPENATTR | OPT | | Section 18.17 |
85 | OPEN_CONFIRM | MNI | | N/A |
86 | OPEN_DOWNGRADE | REQ | | Section 18.18 |
87 | PUTFH | REQ | | Section 18.19 |
88 | PUTPUBFH | REQ | | Section 18.20 |
89 | PUTROOTFH | REQ | | Section 18.21 |
90 | READ | REQ | | Section 18.22 |
91 | READDIR | REQ | | Section 18.23 |
92 | READLINK | OPT | | Section 18.24 |
93NS | RECLAIM_COMPLETE | REQ | | Section 18.51 |
94 | RELEASE_LOCKOWNER | MNI | | N/A |
95 | REMOVE | REQ | | Section 18.25 |
96 | RENAME | REQ | | Section 18.26 |
97 | RENEW | MNI | | N/A |
98 | RESTOREFH | REQ | | Section 18.27 |
99 | SAVEFH | REQ | | Section 18.28 |
100 | SECINFO | REQ | | Section 18.29 |
101NS | SECINFO_NO_NAME | REC | pNFS files | Section 18.45, |
102 | | | layout (REQ) | Section 13.12 |
103I | SEQUENCE | REQ | | Section 18.46 |
104 | SETATTR | REQ | | Section 18.30 |
105 | SETCLIENTID | MNI | | N/A |
106 | SETCLIENTID_CONFIRM | MNI | | N/A |
107NS | SET_SSV | REQ | | Section 18.47 |
108NS | TEST_STATEID | REQ | | Section 18.48 |
109 | VERIFY | REQ | | Section 18.31 |
110NS*| WANT_DELEGATION | OPT | FDELG (OPT) | Section 18.49 |
111 | WRITE | REQ | | Section 18.32 |
112
113Callback Operations
114
115 +-------------------------+-----------+-------------+---------------+
116 | Operation | REQ, REC, | Feature | Definition |
117 | | OPT, or | (REQ, REC, | |
118 | | MNI | or OPT) | |
119 +-------------------------+-----------+-------------+---------------+
120 | CB_GETATTR | OPT | FDELG (REQ) | Section 20.1 |
121P | CB_LAYOUTRECALL | OPT | pNFS (REQ) | Section 20.3 |
122NS*| CB_NOTIFY | OPT | DDELG (REQ) | Section 20.4 |
123P | CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | Section 20.12 |
124NS*| CB_NOTIFY_LOCK | OPT | | Section 20.11 |
125NS*| CB_PUSH_DELEG | OPT | FDELG (OPT) | Section 20.5 |
126 | CB_RECALL | OPT | FDELG, | Section 20.2 |
127 | | | DDELG, pNFS | |
128 | | | (REQ) | |
129NS*| CB_RECALL_ANY | OPT | FDELG, | Section 20.6 |
130 | | | DDELG, pNFS | |
131 | | | (REQ) | |
132NS | CB_RECALL_SLOT | REQ | | Section 20.8 |
133NS*| CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS | Section 20.7 |
134 | | | (REQ) | |
135I | CB_SEQUENCE | OPT | FDELG, | Section 20.9 |
136 | | | DDELG, pNFS | |
137 | | | (REQ) | |
138NS*| CB_WANTS_CANCELLED | OPT | FDELG, | Section 20.10 |
139 | | | DDELG, pNFS | |
140 | | | (REQ) | |
141 +-------------------------+-----------+-------------+---------------+
142
143Implementation notes:
144
145EXCHANGE_ID:
146* only SP4_NONE state protection supported
147* implementation ids are ignored
148
149CREATE_SESSION:
150* backchannel attributes are ignored
151* backchannel security parameters are ignored
152
153SEQUENCE:
154* no support for dynamic slot table renegotiation (optional)
155
156nfsv4.1 COMPOUND rules:
157The following cases aren't supported yet:
158* Enforcing of NFS4ERR_NOT_ONLY_OP for: BIND_CONN_TO_SESSION, CREATE_SESSION,
159 DESTROY_CLIENTID, DESTROY_SESSION, EXCHANGE_ID.
160* DESTROY_SESSION MUST be the final operation in the COMPOUND request.
161
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-18 02:35:55 -0500