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Unix/Linux 中的 Linux 操作系统跑Linux慢的分析


出处:互联网   整理: 软晨网(RuanChen.com)   发布: 2009-11-01   浏览: 79 ::
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挺详细的。是好东东。
  iostat的默认参数是td默认参数将被完全替代,例c(terminal, disk, and CPU)。如,iostat -d将只反 映磁盘的如果任何其他的选项被指定,这个统计结果。   语法:   基本语法: iostat interval count   option - 让你指定所。x 选项给出了完整的统计需信息的设备,像磁盘、cpu或结果(gives the extended 者终端(-d , -c , -t or -tdc )   statistic)。   interval - 在两个samples之间的时间(秒)。   count - 就是需要统计几次   例子:   $ iostat -xtc 5 2   extended disk statistics tty cpu   disk r/s w/s Kr/s Kw/s wait actv svc_t %w %b tintout us sy wt id   sd0 2.6 3.0 20.7 22.7 0.1 0.2 59.2 6 19 0 84 3 85 11 0   sd1 4.2 1.0 33.5 8.0 0.0 0.2 47.2 2 23   sd2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0   sd3 10.2 1.6 51.4 12.8 0.1 0.3 31.2 3 31   The fields have the following meanings:   disk name of the disk   r/s reads per second   w/s writes per second   Kr/s kilobytes read per second   Kw/s kilobytes written per second   wait average number of transactions waiting for service (Q length)   actv average number of transactions actively   being serviced (removed from the   queue but not yet   completed)   %w percent of time there are transactions waiting   for service (queue non-empty)   %b percent of time the disk is busy (transactions   in progress)   Results and Solutions:   从iostat输出结果中需要注意的值:   Reads/writes per second (r/s , w/s)   Percentage busy (%b)   Service time (svc_t)   如果磁盘显示长时间的高reads/writ同时average service time (svc_t)也远es,并且磁盘的percentage busy (%b)也远大于5%,大于30   milliseconds,这以下的措施需要被执行:   1.)调整应用,令其使用磁盘i/o更加cache 有效率,可以通过修改磁盘队列、使用应用服务器的  2.)将文件系统分布到2个或多个磁盘上,并使用volumemanager/disksuite的条带化特点  3.) 增加系统参数值,values for inode cache ,如inode cache , ufs_ninode。ufs_ninode , which Increase the system parameter   is Number of inodes to be held iUFS), not on a per-file system basisn memory. Inodes are cached globally (for   4.) 将文件系统移到更快的磁盘/控制器,或者用更好的设备来代替   vmstat - vmstat反映?)和cpu的活动情况 了进程的虚拟内存、虚拟内存、磁盘、trap(是不是翻译成中断?  在多cpu系统中,vmsta果没有选项,vmstat显示一t在输出结果中平均了cpu数量。行虚拟内存活动的概要 For per-process statistics .如  结果,是从系统启动时开始的。   语法:   vmstat interval count   option - 让你指定所需的信息类型etc. ,例如 paging -p , cache -c ,.interrupt -i   如果没有指定选项,将会显示进程、内存、页、磁盘、中断和cpu信息   interval - 同iostat   count - 同iostat   例子   The following command displays a summary of whatthe system   is doing every five seconds.   example% vmstat 5   procs memory page disk faults cpu   r b w swap free re mf pi p fr desr s0 s1 s2 s3 in sy cs us sy id   0 0 0 11456 4120 1 41 19 1 3 0 2 0 4 0 0 48 112 130 4 14 82   0 0 1 10132 4280 0 444 0 0 0 0 0 23 0 0 211 230144 3 35 62   0 0 1 10132 4616 0 0 20 0 0 0 0 0 19 0 0 150 172 146 3 33 64   0 0 1 10132 5292 0 09 0 0 0 0 0 21 0 0 165 105 130 1 21 78   The fields of vmstat's display are   procs   r in run queue   b blocked for resources I/O, paging etc.   w swapped   memory (in Kbytes)   swap - amount of swap space currently available   free - size of the free list   page ( in units per second).   re page reclaims - see -S option for how this field is modified.   mf minor faults - see -S option for how this field is modified.   pi kilobytes paged in   po kilobytes paged out   fr kilobytes freed   de anticipated short-term memoryshortfall (Kbytes)   sr pages scanned by clock algorithm   disk ( operations per second )   There are slots for up to four disks, labeled with a single letter and number.  The letter indicatesthe type of disk (s = SCSI,i = IPI, etc) . The number is  the logical unit number.   faults   in (non clock) device interrupts   sy system calls   cs CPU context switches   cpu - breakdown of pan a ercentage usage of CPU time.On multiprocessors this is   verage across all p