linux分析、診斷及調優的必備“殺器”
1、top
top - 02:06:59 up 4 days, 17:14, 2 users, load average: 0.00, 0.00, 0.00
Tasks: 62 total, 1 running, 61 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.2% us, 0.3% sy, 0.0% ni, 97.8% id, 1.7% wa, 0.0% hi, 0.0% si
Mem: 515144k total, 317624k used, 197520k free, 66068k buffers
Swap: 1048120k total, 12k used, 1048108k free, 179632k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
13737 root 17 0 1760 896 1540 R 0.7 0.2 0:00.05 top
238 root 5 -10 0 0 0 S 0.3 0.0 0:01.56 reiserfs/0
1 root 16 0 588 240 444 S 0.0 0.0 0:05.70 init
2 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/0
3 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/0
4 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/1
5 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/1
6 root 5 -10 0 0 0 S 0.0 0.0 0:00.02 events/0
輸出列說明：
PID：Process identification.
USER：Name of the user who owns (and perhaps started) the process.
PRI：Priority of the process. (See 1.1.4, “Process priority and nice level” on page 5 for details.)
SIZE：Amount of memory (code+data+stack) used by the process in kilobytes.
RSS：Amount of physical RAM used, in kilobytes.
SHARE：Amount of memory shared with other processes, in kilobytes.
STAT：State of the process: S=sleeping, R=running, T=stopped or traced,D=interruptible sleep, Z=zombie.
%CPU：Share of the CPU usage (since the last screen update).
%MEM：Share of physical memory.
TIME：Total CPU time used by the process (since it was started).
COMMAND：Command line used to start the task (including parameters).
有用的熱鍵：
t ：Displays summary information off and on.
m ：Displays memory information off and on.
A ：Sorts the display by top consumers of various system resources. Useful for quick identification of performance-hungry tasks on a system.
f ：Enters an interactive configuration screen for top. Helpful for setting up top for a specific task.
o ：Enables you to interactively select the ordering within top.
r ：Issues renice command.
k ：Issues kill command.
O or F：enters an interactive configuration screen for processes order.
h：displays help screen.
2、vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 1 0 1742264 112116 1999864 0 0 1 4 3 3 0 0 99 0
0 1 0 1742072 112208 1999772 0 0 0 2536 1258 1146 0 1 75 24
0 1 0 1741880 112260 1999720 0 0 0 2668 1235 1002 0 1 75 24
0 1 0 1741560 112308 1999932 0 0 0 2930 1240 1015 0 1 75 24
1 1 0 1741304 112344 2000416 0 0 0 2980 1238 925 0 1 75 24
0 1 0 1741176 112384 2000636 0 0 0 2968 1233 929 0 1 75 24
0 1 0 1741304 112420 2000600 0 0 0 3024 1247 925 0 1 75 24
輸出列說明：
Process (procs) r:The number of processes waiting for runtime
b: The number of processes in uninterruptable sleep
Memory swpd: The amount of virtual memory used (KB)
free: The amount of idle memory (KB)
buff: The amount of memory used as buffers (KB)
cache: The amount of memory used as cache (KB)
Swap si: Amount of memory swapped from the disk (KBps)
so: Amount of memory swapped to the disk (KBps)
IO bi: Blocks sent to a block device (blocks/s)
bo: Blocks received from 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 (% 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 included I/O-wait time.
wa: Time spent waiting for IO. Prior to Linux 2.5.41, this appeared as zero.
有用的命令行參數：
-m:displays the memory utilization of the kernel (slabs)
-a:provides information about active and inactive memory pages
-n:displays only one header line, useful if running vmstat in sampling mode and piping the output to a file. (For example, root#vmstat –n 2 10 generates vmstat 10 times with a sampling rate of two seconds.)When used with the –p {partition} flag, vmstat also provides I/O statistics.
3、uptime
10:12:37 up 244 days, 26 min, 1 user, load average: 10.92, 23.68, 23.64
說明：
The uptime command can be used to see how long the server has been running and how many users are logged on, as well as for a quick overview of the average load of the server.The system load average is displayed for the past 1minute, 5 minute, and 15 minute intervals.
4、ps
有用的命令選項：
-e:All processes. Identical to -A
-l:Show long format
-F:Extra full mode
-H:Forest
-L:Show threads, possibly with LWP and NLWP columns
-m:Show threads after processes
root# ps -elFL
F S UID PID PPID LWP C NLWP PRI NI ADDR SZ WCHAN RSS PSR STIME TTY TIME CMD
4 S root 1 0 1 0 1 76 0 - 457 - 552 0 Mar08 ? 00:00:01 init [3]
1 S root 2 1 2 0 1 -40 - - 0 migrat 0 0 Mar08 ? 00:00:36 [migration/0]
1 S root 3 1 3 0 1 94 19 - 0 ksofti 0 0 Mar08 ? 00:00:00 [ksoftirqd/0]
root# ps -eLF| grep -E "LWP|/usr/sbin/httpd"
UID PID PPID LWP C NLWP SZ RSS PSR STIME TTY TIME CMD
root 4504 1 4504 0 1 4313 8600 2 08:33 ? 00:00:00 /usr/sbin/httpd
apache 4507 4504 4507 0 1 4313 4236 1 08:33 ? 00:00:00 /usr/sbin/httpd
apache 4508 4504 4508 0 1 4313 4228 1 08:33 ? 00:00:00 /usr/sbin/httpd
輸出列說明：
F:Process flag
S:State of the process: S=sleeping, R=running, T=stopped or traced,D=interruptable sleep, Z=zombie.
UID:Name of the user who owns (and perhaps started) the process.
PID:Process ID number
PPID:Parent process ID number
LWP:LWP(light weight process, or thread) ID of the lwp being reported.
C:Integer value of the processor utilization percentage.(CPU usage)
NLWP:Number of lwps (threads) in the process. (alias thcount).
PRI:Priority of the process.
NI:Niceness level (whether the process tries to be nice by adjusting the priority by the number given; see below for details).
ADDR:Process Address space (not displayed)
SZ:Amount of memory (code+data+stack) used by the process in kilobytes.
WCHAN:Name of the kernel function in which the process is sleeping, a “-” if the process is running, or a “*” if the process is multi-threaded and ps is not displaying threads.
RSS:Resident set size, the non-swapped physical memory that a task has used (in kiloBytes).
PSR:Processor that process is currently assigned to.
STIME:Time the command started.
TTY:Terminal
TIME:Total CPU time used by the process (since it was started).
CMD:Command line used to start the task (including parameters).
5、free
有用的命令參數：
-b, -k, -m, -g:Display values in bytes, kilobytes, megabytes, and gigabytes
-l:Distinguishes between low and high memory
-c <count>:Displays the free output <count> number of times
[root@edam ~]# free -l
total used free shared buffers cached
Mem: 4154484 2381500 1772984 0 108256 1974344
Low: 877828 199436 678392
High: 3276656 2182064 1094592
-/+ buffers/cache: 298900 3855584
Swap: 4194296 0 4194296
