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