VMSTAT(8) System Administration VMSTAT(8) NAME vmstat - Report virtual memory statistics SYNOPSIS vmstat [options] [delay [count]] DESCRIPTION vmstat reports information about processes, memory, paging, block IO, traps, disks and cpu activity. The first report produced gives averages since the last reboot. Additional reports give information on a sam‐ pling period of length delay. The process and memory reports are instantaneous in either case. OPTIONS delay The delay between updates in seconds. If no delay is specified, only one report is printed with the average values since boot. count Number of updates. In absence of count, when delay is defined, default is infinite. -a, --active Display active and inactive memory, given a 2.5.41 kernel or better. -f, --forks The -f 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. -m, --slabs Displays slabinfo. -n, --one-header Display the header only once rather than periodically. -s, --stats Displays a table of various event counters and memory statistics. This display does not repeat. -d, --disk Report disk statistics (2.5.70 or above required). -D, --disk-sum Report some summary statistics about disk activity. -p, --partition device Detailed statistics about partition (2.5.70 or above required). -S, --unit character Switches outputs between 1000 (k), 1024 (K), 1000000 (m), or 1048576 (M) bytes. Note this does not change the swap (si/so) or block (bi/bo) fields. -t, --timestamp Append timestamp to each line -w, --wide Wide output mode (useful for systems with higher amount of memory, where the default output mode suf‐ fers from unwanted column breakage). The output is wider than 80 characters per line. -V, --version 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) Swap si: Amount of memory swapped in from disk (/s). so: Amount of memory swapped to disk (/s). IO bi: Blocks received from a block device (blocks/s). bo: Blocks sent to a block device (blocks/s). System in: The number of interrupts per second, including the clock. cs: The number of context switches per second. CPU These are percentages of total CPU time. 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. FIELD DESCRIPTION FOR DISK MODE Reads total: Total reads completed successfully merged: grouped reads (resulting in one I/O) sectors: Sectors read successfully ms: milliseconds spent reading Writes total: Total writes completed successfully merged: grouped writes (resulting in one I/O) sectors: Sectors written successfully ms: milliseconds spent writing IO cur: I/O in progress s: seconds spent for I/O FIELD DESCRIPTION FOR DISK PARTITION MODE 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 FIELD DESCRIPTION FOR SLAB MODE cache: Cache name num: Number of currently active objects total: Total number of available objects size: Size of each object vmstat uses slabinfo 1.1 FILES /proc/meminfo /proc/stat /proc/*/stat SEE ALSO free(1), iostat(1), mpstat(1), ps(1), sar(1), top(1) BUGS Does not tabulate the block io per device or count the number of system calls. AUTHORS Written by Henry Ware ⟨[email protected]⟩. Fabian Frédérick ⟨[email protected]⟩ (diskstat, slab, partitions...) REPORTING BUGS Please send bug reports to ⟨[email protected]⟩ procps-ng September 2011 VMSTAT(8)