Performance Tuning

10 years ago, when computing equipment was much more costly, performance tuning consisted mostly of adjusting the computer to work with the hardware installed. Today, it is often easier to add faster or more hardware rather then tweak the OS.

bigger, faster, better

• memory/swap
• disk
• cpu
• network

know where your bottlenecks are

buying a faster CPU, when the CPU is mostly idle, does not help

• activity
• useage
• availability

collect statistics for a baseline

• free memory/swap
• pages swapped vs. time
• cpu usage (user and system)
• load average
• io such as disk usage and network usage

problems

• thrashing
• out of resources (memory, disk, cpu, ...)
• bottlenecks

tools

• users
• sar
• time
• uptime
• vmstat

  rainbow kscott >vmstat -S 10
   procs     memory            page            disk          faults      cpu
   r b w   swap  free  si  so pi po fr de sr f0 s3 -- --   in   sy   cs us sy id
   0 0 0   5840   908   0   0 25  5 15 700 7  0  2  0  0  152 1979  203  9 11 80
   0 0 0 170908  3356   0   0  0  0  0  0  0  0  0  0  0  443 5961 3187 12 44 44
   0 0 0 170896  3344   0   0  1  0  0  0  0  0  0  0  0  449 6034 3340 14 44 42
   0 0 0 170872  3320   0   0  0  0  0  0  0  0  2  0  0  455 6063 3270 14 45 41
   0 0 0 170820  3264   0   0  0  0  0  0  0  0  3  0  0  407 5925 3508 13 44 43
  

• iostat

  rainbow kscott >iostat 1
        tty          fd0           sd3          nfs1          nfs2          cpu
   tin tout kps tps serv  kps tps serv  kps tps serv  kps tps serv  us sy wt id
     8  466   0   0    0   17   2   67    0   0   13    0   0    1   9 11  0 79
     0 6825   0   0    0    4   1   15    0   0    0    0   0    0  13 49  0 38
     1 7702   0   0    0    0   0    0    0   0    0    0   0    0  17 43  0 40
  

• syslog
• du/df
• tcpdump