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$ vmstat?1?100

procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------

?r? b?? swpd?? free?? buff? cache?? si?? so??? bi??? bo?? in?? cs us sy id wa st

?0??0?????88?233484?288756?1784744????0????0?????0????23????0????0??4??1?94??0??0

?4??0?????88?233236?288756?1784752????0????0?????0?????0?6202?7880??4??1?96??0??0

?2??0?????88?233360?288756?1784800????0????0?????0???112?6277?7612??4??1?95??0??0

?0??0?????88?232864?288756?1784804????0????0?????0???644?5747?6593??6??0?92??2??0

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linux:~ # pidstat

Linux?2.6.32.12-0.7-default?(linux)?????????????06/18/12????????_x86_64_

?

11:37:19??????????PID??? %usr %system? %guest??? %CPU?? CPU? Command

……

11:37:19????????11452????0.00????0.00????0.00????0.00?????2??bash

11:37:19????????11509????0.00????0.00????0.00????0.00?????3??dd

11:37:19:?pidstat獲取信息時間點

PID: 進程pid

%usr: 進程在用戶態運行所占cpu時間比率

%system: 進程在內核態運行所占cpu時間比率

%CPU: 進程運行所占cpu時間比率

CPU: 指示進程在哪個核運行

Command: 拉起進程對應的命令

備注:執行pidstat默認輸出信息為系統啟動后到執行時間點的統計信息，因而即使當前某進程的cpu占用率很高，輸出中的值有可能仍為0。

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#wget http://www.bitmover.com/lmbench/lmbench3.tar.gz

#tar -zxvf lmbench3.tar.gz

#cd lmbench3

#make

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此時會報錯：

???make[2]: *** 沒有規則可以創建“bk.ver”需要的目標“../SCCS/s.ChangeSet”。 停止。

???make[2]:正在離開目錄 `/home/hero/lmbench3/src'

???make[1]: *** [lmbench] 錯誤 2

???make[1]:正在離開目錄 `/home/hero/lmbench3/src'

???make: *** [build] 錯誤 2

解決辦法：

lmbench3目錄下

???#mkdir SCCS

???#touch? ./SCCS/s.ChangeSet

???#make

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Context switching - times in microseconds -?smaller?is better

-------------------------------------------------------------------------

Host???????????????? OS??2p/0K?2p/16K?2p/64K?8p/16K?8p/64K?16p/16K?16p/64K

?????????????????????????ctxsw? ctxsw? ctxsw ctxsw? ctxsw?? ctxsw?? ctxsw

--------- ------------- ------ ------ ------ ------ ------ ------- -------

commonway Linux?2.6.18-?9.2400?4.0200?9.0300?7.5600?8.3800????11.6?6.28000

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The benchmark is a ring of two to twenty processes that are connected

with Unix pipes.? A token is passed from process to process, forcing

context switches.? The benchmark measures the time it takes to pass

the token two thousand times from process to process.? Each hand off

of the token has two costs: (a) the context switch, and (b) the cost

of passing the token.? In order to get just the context switching time,the benchmark first measures the cost of passing the token through a

ring of pipes in a single process.? This time is defined as the cost

of passing the token and is not included in the reported context switch

time.

.PP

????When the processes are?larger?than the?default?baseline?of ``zero''

(where zero means just big enough to do the benchmark), the cost

of the context switch includes the cost of restoring user?level

state (cache lines).? This is accomplished by having the process

allocate an array of data and sum it as a series of integers

after receiving the token but before passing the token to the

next process.? Note that the overhead mentioned?above?includes

the cost of accessing the data but because it is measured in

just one address space, the cost is typically the cost with hot

caches.? So the context switch time does not include anything

other than the context switch provided that?all?the processes

fit in the cache.? If there are cache misses (as is common), the

cost of the context switch includes the cost of those cache misses.

.PP

????首先是看任務處理的時間（通過一次任務處理，這個任務處理的時間被定義為token時間，不包括線程切換的）。

????然后多次執行，排除任務執行的時間，然后計算出CS的時間（如果有cache miss，則CS的時間也包括cache misses的時間）。