232 lines
5.6 KiB
Groff
232 lines
5.6 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 "2020-06-04" "procps-ng" "System Administration"
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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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.B vmstat
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[options]
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.RI [ delay " [" count ]]
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.SH DESCRIPTION
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.B vmstat
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reports information about processes, memory, paging, block IO, traps, disks
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and cpu activity.
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.PP
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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
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.IR delay .
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The process and memory reports are instantaneous in either case.
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.SH OPTIONS
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.TP
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.I delay
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The
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.I delay
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between updates in seconds. If no
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.I delay
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is specified, only one report is printed with the average values since boot.
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.TP
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.I count
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Number of updates. In absence of
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.IR count ,
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when
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.I delay
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is defined, default is infinite.
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.TP
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\fB\-a\fR, \fB\-\-active\fR
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Display active and inactive memory, given a 2.5.41 kernel or better.
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.TP
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\fB\-f\fR, \fB\-\-forks\fR
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The
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.B \-f
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switch displays the number of forks since boot. This includes the fork,
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vfork, and clone system calls, and is equivalent to the total number of tasks
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created. Each process is represented by one or more tasks, depending on
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thread usage. This display does not repeat.
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.TP
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\fB\-m\fR, \fB\-\-slabs\fR
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Displays slabinfo.
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.TP
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\fB\-n\fR, \fB\-\-one-header\fR
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Display the header only once rather than periodically.
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.TP
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\fB\-s\fR, \fB\-\-stats\fR
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Displays a table of various event counters and memory statistics. This
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display does not repeat.
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.TP
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\fB\-d\fR, \fB\-\-disk\fR
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Report disk statistics (2.5.70 or above required).
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.TP
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\fB\-D\fR, \fB\-\-disk-sum\fR
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Report some summary statistics about disk activity.
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.TP
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\fB\-p\fR, \fB\-\-partition\fR \fIdevice\fR
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Detailed statistics about partition (2.5.70 or above required).
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.TP
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\fB\-S\fR, \fB\-\-unit\fR \fIcharacter\fR
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Switches outputs between 1000
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.RI ( k ),
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1024
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.RI ( K ),
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1000000
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.RI ( m ),
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or 1048576
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.RI ( M )
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bytes. Note this does not change the swap (si/so) or block (bi/bo)
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fields.
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.TP
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\fB\-t\fR, \fB\-\-timestamp\fR
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Append timestamp to each line
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.TP
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\fB\-w\fR, \fB\-\-wide\fR
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Wide output mode (useful for systems with higher amount of memory,
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where the default output mode suffers from unwanted column breakage).
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The output is wider than 80 characters per line.
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.TP
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\fB\-V\fR, \fB\-\-version\fR
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Display version information and exit.
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.TP
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\fB\-h\fR, \fB\-\-help\fR
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Display help and exit.
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.PD
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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 runnable processes (running or 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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These are affected by the \fB\-\-unit\fR option.
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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. (\fB\-a\fR option)
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active: the amount of active memory. (\fB\-a\fR 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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These are affected by the \fB\-\-unit\fR option.
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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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.fi
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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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.fi
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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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.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 blocks as
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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
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(1024 bytes) in the default mode.
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.PP
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vmstat uses slabinfo 1.1
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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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.BR free (1),
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.BR iostat (1),
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.BR mpstat (1),
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.BR ps (1),
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.BR sar (1),
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.BR top (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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Written by
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.UR al172@yfn.\:ysu.\:edu
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Henry Ware
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.UE .
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.br
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.UR ffrederick@users.\:sourceforge.\:net
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Fabian Fr\('ed\('erick
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.UE
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(diskstat, slab, partitions...)
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.SH "REPORTING BUGS"
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Please send bug reports to
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.UR procps@freelists.org
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.UE
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