Unix vmstat 命令详解宝典(unix vi命令)

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在一个多CPU系统中,vmstat统计所有个数的CPU的平均输出.为每个进程进行统计.没有参数时,vmstat显示每一行是自从系统启动以后的虚拟内存的活动情况. vmstat 的语法我们可以通过linux的man 命令来查看。 将man 的结果导入到指定的文本 # man vmstat|col -b > /u/tianlesoftware.txt 查看vmstat 用法 # man vmstat VMSTAT(8) Linux Administrator’s Manual VMSTAT(8) NAME vmstat - Report virtual memory statistics SYNOPSIS vmstat [-a] [-n] [delay [ count]] vmstat [-f] [-s] [-m] vmstat [-S unit] vmstat [-d] vmstat [-p disk partition] vmstat [-V] DESCRIPTION vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity. The first report produced gives averages since the last reboot. Addi- tional reports give information on a sampling period of length delay. The process and memory reports are instantaneous in either case. Options The -a switch displays active/inactive memory, given a 2.5. kernel or better. 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. The -m displays slabinfo. The -n switch causes the header to be displayed only once rather than periodically. The -s switch displays a table of various event counters and memory statistics. This display does not repeat. delay is the delay between updates in seconds. If no delay is speci- fied, only one report is printed with the average values since boot. count is the number of updates. If no count is specified and delay is defined, count defaults to infinity. The -d reports disk statistics (2.5. or above required) The -p followed by some partition name for detailed statistics (2.5. or above required) The -S followed by k or K or m or M switches outputs between , , , or bytes The -V switch results in displaying version information. FIELD DESCRIPTION FOR VM MODE Procs r: The number of processes waiting for run time. b: The number of processes in uninterruptible sleep. Memory 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) 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., this includes IO-wait time. wa: Time spent waiting for IO. Prior to Linux 2.5., shown as zero. 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 pages: Number of pages with at least one active object totpages: Total number of allocated pages pslab: Number of pages per slab NOTES vmstat does not require special permissions. These reports are intended to help identify system bottlenecks. Linux vmstat does not count itself as a running process. All linux blocks are currently bytes. Old kernels may report blocks as bytes, bytes, or bytes. Since procps 3.1.9, vmstat lets you choose units (k, K, m, M) default is K ( bytes) in the default mode vmstat uses slabinfo 1.1 FIXME FILES /proc/meminfo /proc/stat /proc/*/stat SEE ALSO iostat(1), sar(1), mpstat(1), ps(1), top(1), free(1) BUGS Does not tabulate the block io per device or count the number of sys- tem calls. AUTHORS Written by Henry Ware <al@yfn.ysu.edu>. Fabian Frédérick <ffrederick@users.sourceforge.net> (diskstat, slab, partitions...) Throatwobbler Ginkgo Labs July VMSTAT(8) 示例： # vmstat 2 procs -----------memory---------------------- -----swap--- -----io---- ---system--- ----cpu------ r b swpd free buff cache si so bi bo in cs us sy id wa 1 1 0 0 5 5 1 0 0 0 0 4 1 2 0 0 0 4 5 2 0 0 0 1 6 7 0 0 0 0 0 4 5 0 0 0 0 3 1 1 0 0 0 9 1 1 0 0 0 1 6 2 0 0 0 0 1 5 1 0 0 0 0 4 5 每2秒显示一次，共显示次。 在Unix(Solaris)平台下： -bash-3.$ vmstat 2 kthr memory page disk faults cpu r b w swap free re mf pi po fr de sr s0 s1 -- -- in sy cs us sy id 0 0 0 0 0 0 0 0 1 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 4 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 4 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 一些标准说明： CPU: 1) 如果(process r)是连续的大于在系统中的CPU的个数表示系统现在运行比较慢,有多数的进程等待CPU. 2) 如果r的输出数大于系统中可用CPU个数的4倍的话,则系统面临着CPU短缺的问题,或者是CPU的速率过低,系统中有多数的进程在等待CPU,造成系统中进程运行过慢. 3) 如果空闲时间(cpu id)持续为0并且系统时间(cpu sy)是用户时间的两倍(cpu us) 系统则面临着CPU资源的短缺. 简单的说就是： r 和 b 不高于5，如果r 经常大于4，且id 经常少于，则表示CPU 负荷很重。 us+sy 不超过%，如果大于，进程就会在运行队列中花费等待时间，响应时间和吞吐量就会下降。 wa 不超过， 如果说wa >表明磁盘io没有也许存在不合理的平衡，或者对磁盘操作比较频繁 一般情况下，导致CPU资源不足都是应用程序的问题.比如一些SQL语句不合理等等都会造成这样的现象. 内存： si和so基本为零。 其中si表示当前每秒交换回内存（Swap in）的总量，单位为kbytes；so表示当前每秒交换出内存（Swap out）的总量，单位为kbytes。如果si，so 长期不等于0，表示系统使用swap 频繁，即内存不足。 一般情况下，如果内存的占用率比较高,但是,CPU的占用很低的时候,可以考虑是有很多的应用程序占用了内存没有释放. 要注意的是，Linux 内存在使用后不会释放，所以一般会看到内存使用率很高，要判断linux 内存是否正常，需要通过对swap 交换区的交换频率来看。

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