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| -rw-r--r-- | Documentation/filesystems/nfs/knfsd-stats.txt | 123 |
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diff --git a/Documentation/filesystems/nfs/knfsd-stats.txt b/Documentation/filesystems/nfs/knfsd-stats.txt deleted file mode 100644 index 1a5d82180b84..000000000000 --- a/Documentation/filesystems/nfs/knfsd-stats.txt +++ /dev/null @@ -1,123 +0,0 @@ - -Kernel NFS Server Statistics -============================ - -This document describes the format and semantics of the statistics -which the kernel NFS server makes available to userspace. These -statistics are available in several text form pseudo files, each of -which is described separately below. - -In most cases you don't need to know these formats, as the nfsstat(8) -program from the nfs-utils distribution provides a helpful command-line -interface for extracting and printing them. - -All the files described here are formatted as a sequence of text lines, -separated by newline '\n' characters. Lines beginning with a hash -'#' character are comments intended for humans and should be ignored -by parsing routines. All other lines contain a sequence of fields -separated by whitespace. - -/proc/fs/nfsd/pool_stats ------------------------- - -This file is available in kernels from 2.6.30 onwards, if the -/proc/fs/nfsd filesystem is mounted (it almost always should be). - -The first line is a comment which describes the fields present in -all the other lines. The other lines present the following data as -a sequence of unsigned decimal numeric fields. One line is shown -for each NFS thread pool. - -All counters are 64 bits wide and wrap naturally. There is no way -to zero these counters, instead applications should do their own -rate conversion. - -pool - The id number of the NFS thread pool to which this line applies. - This number does not change. - - Thread pool ids are a contiguous set of small integers starting - at zero. The maximum value depends on the thread pool mode, but - currently cannot be larger than the number of CPUs in the system. - Note that in the default case there will be a single thread pool - which contains all the nfsd threads and all the CPUs in the system, - and thus this file will have a single line with a pool id of "0". - -packets-arrived - Counts how many NFS packets have arrived. More precisely, this - is the number of times that the network stack has notified the - sunrpc server layer that new data may be available on a transport - (e.g. an NFS or UDP socket or an NFS/RDMA endpoint). - - Depending on the NFS workload patterns and various network stack - effects (such as Large Receive Offload) which can combine packets - on the wire, this may be either more or less than the number - of NFS calls received (which statistic is available elsewhere). - However this is a more accurate and less workload-dependent measure - of how much CPU load is being placed on the sunrpc server layer - due to NFS network traffic. - -sockets-enqueued - Counts how many times an NFS transport is enqueued to wait for - an nfsd thread to service it, i.e. no nfsd thread was considered - available. - - The circumstance this statistic tracks indicates that there was NFS - network-facing work to be done but it couldn't be done immediately, - thus introducing a small delay in servicing NFS calls. The ideal - rate of change for this counter is zero; significantly non-zero - values may indicate a performance limitation. - - This can happen because there are too few nfsd threads in the thread - pool for the NFS workload (the workload is thread-limited), in which - case configuring more nfsd threads will probably improve the - performance of the NFS workload. - -threads-woken - Counts how many times an idle nfsd thread is woken to try to - receive some data from an NFS transport. - - This statistic tracks the circumstance where incoming - network-facing NFS work is being handled quickly, which is a good - thing. The ideal rate of change for this counter will be close - to but less than the rate of change of the packets-arrived counter. - -threads-timedout - Counts how many times an nfsd thread triggered an idle timeout, - i.e. was not woken to handle any incoming network packets for - some time. - - This statistic counts a circumstance where there are more nfsd - threads configured than can be used by the NFS workload. This is - a clue that the number of nfsd threads can be reduced without - affecting performance. Unfortunately, it's only a clue and not - a strong indication, for a couple of reasons: - - - Currently the rate at which the counter is incremented is quite - slow; the idle timeout is 60 minutes. Unless the NFS workload - remains constant for hours at a time, this counter is unlikely - to be providing information that is still useful. - - - It is usually a wise policy to provide some slack, - i.e. configure a few more nfsds than are currently needed, - to allow for future spikes in load. - - -Note that incoming packets on NFS transports will be dealt with in -one of three ways. An nfsd thread can be woken (threads-woken counts -this case), or the transport can be enqueued for later attention -(sockets-enqueued counts this case), or the packet can be temporarily -deferred because the transport is currently being used by an nfsd -thread. This last case is not very interesting and is not explicitly -counted, but can be inferred from the other counters thus: - -packets-deferred = packets-arrived - ( sockets-enqueued + threads-woken ) - - -More ----- -Descriptions of the other statistics file should go here. - - -Greg Banks <gnb@sgi.com> -26 Mar 2009 |