199 lines
5.1 KiB
Groff
199 lines
5.1 KiB
Groff
.\" This page Copyright (C) 1994 Henry Ware <al172@yfn.ysu.edu>
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.\" Distributed under the GPL, Copyleft 1994.
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.TH VMSTAT 8 "27 July 1994 " "Throatwobbler Ginkgo Labs" "Linux Administrator's Manual"
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.SH NAME
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vmstat \- Report virtual memory statistics
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.SH SYNOPSIS
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.ft B
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.B vmstat
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.RB [ "\-a" ]
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.RB [ "\-n" ]
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.RI [ delay " [ " count ]]
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.br
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.B vmstat
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.RB [ "\-f" ]
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.RB [ "\-s" ]
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.RB [ "\-m" ]
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.br
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.B vmstat
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.RB [ "\-S unit"]
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.br
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.B vmstat
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.RB [ "\-d"]
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.br
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.B vmstat
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.RB [ "\-p disk partition"]
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.br
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.B vmstat
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.RB [ "\-V" ]
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.SH DESCRIPTION
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\fBvmstat\fP reports information about processes, memory, paging,
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block IO, traps, and cpu activity.
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The first report produced gives averages since the last reboot. Additional
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reports give information on a sampling period of length \fIdelay\fP.
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The process and memory reports are instantaneous in either case.
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.SS Options
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The \fB-a\fP switch displays active/inactive memory, given a 2.5.41 kernel or better.
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.PP
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The \fB-f\fP switch displays the number of forks since boot.
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This includes the fork, vfork, and clone system calls, and is
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equivalent to the total number of tasks created. Each process
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is represented by one or more tasks, depending on thread usage.
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This display does not repeat.
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.PP
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The \fB-m\fP displays slabinfo.
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.PP
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The \fB-n\fP switch causes the header to be displayed only once rather than periodically.
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.PP
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The \fB-s\fP switch displays a table of various event counters
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and memory statistics. This display does not repeat.
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.PP
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.I delay
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is the delay between updates in seconds. If no delay is specified,
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only one report is printed with the average values since boot.
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.PP
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.I count
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is the number of updates. If no count is specified and delay is
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defined, \fIcount\fP defaults to infinity.
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.PP
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The \fB-d\fP reports disk statistics (2.5.70 or above required)
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.PP
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The \fB-p\fP followed by some partition name for detailed statistics (2.5.70 or above required)
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.PP
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The \fB-S\fP followed by k or K or m or M switches outputs between 1000, 1024, 1000000, or 1048576 bytes
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.PP
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The \fB-V\fP switch results in displaying version information.
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.PP
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.SH FIELD DESCRIPTION FOR VM MODE
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.SS
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.B "Procs"
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.nf
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r: The number of processes waiting for run time.
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b: The number of processes in uninterruptible sleep.
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.fi
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.PP
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.SS
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.B "Memory"
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.nf
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swpd: the amount of virtual memory used.
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free: the amount of idle memory.
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buff: the amount of memory used as buffers.
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cache: the amount of memory used as cache.
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inact: the amount of inactive memory. (-a option)
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active: the amount of active memory. (-a option)
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.fi
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.PP
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.SS
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.B "Swap"
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.nf
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si: Amount of memory swapped in from disk (/s).
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so: Amount of memory swapped to disk (/s).
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.fi
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.PP
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.SS
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.B "IO"
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.nf
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bi: Blocks received from a block device (blocks/s).
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bo: Blocks sent to a block device (blocks/s).
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.fi
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.PP
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.SS
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.B "System"
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.nf
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in: The number of interrupts per second, including the clock.
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cs: The number of context switches per second.
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.if
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.PP
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.SS
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.B "CPU "
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These are percentages of total CPU time.
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.nf
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us: Time spent running non-kernel code. (user time, including nice time)
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sy: Time spent running kernel code. (system time)
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id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
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wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
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st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.
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.PP
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.SH FIELD DESCRIPTION FOR DISK MODE
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.SS
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.B "Reads"
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.nf
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total: Total reads completed successfully
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merged: grouped reads (resulting in one I/O)
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sectors: Sectors read successfully
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ms: milliseconds spent reading
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.fi
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.PP
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.SS
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.B "Writes"
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.nf
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total: Total writes completed successfully
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merged: grouped writes (resulting in one I/O)
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sectors: Sectors written successfully
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ms: milliseconds spent writing
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.fi
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.PP
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.SS
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.B "IO"
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.nf
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cur: I/O in progress
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s: seconds spent for I/O
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.fi
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.PP
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.SH FIELD DESCRIPTION FOR DISK PARTITION MODE
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.nf
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reads: Total number of reads issued to this partition
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read sectors: Total read sectors for partition
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writes : Total number of writes issued to this partition
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requested writes: Total number of write requests made for partition
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.fi
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.PP
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.SH FIELD DESCRIPTION FOR SLAB MODE
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.nf
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cache: Cache name
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num: Number of currently active objects
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total: Total number of available objects
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size: Size of each object
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pages: Number of pages with at least one active object
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totpages: Total number of allocated pages
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pslab: Number of pages per slab
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.fi
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.SH NOTES
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.B "vmstat "
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does not require special permissions.
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.PP
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These reports are intended to help identify system bottlenecks. Linux
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.B "vmstat "
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does not count itself as a running process.
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.PP
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All linux blocks are currently 1024 bytes. Old kernels may report
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blocks as 512 bytes, 2048 bytes, or 4096 bytes.
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.PP
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Since procps 3.1.9, vmstat lets you choose units (k, K, m, M) default is K (1024 bytes) in the default mode
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.PP
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vmstat uses slabinfo 1.1 FIXME
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.SH FILES
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.ta
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.nf
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/proc/meminfo
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/proc/stat
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/proc/*/stat
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.fi
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.SH "SEE ALSO"
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iostat(1), sar(1), mpstat(1), ps(1), top(1), free(1)
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.PP
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.SH BUGS
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Does not tabulate the block io per device or count the number of system calls.
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.SH AUTHORS
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.nf
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Written by Henry Ware <al172@yfn.ysu.edu>.
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Fabian Fr\('ed\('erick <ffrederick@users.sourceforge.net> (diskstat, slab, partitions...)
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