Tuesday, May 19, 2009

vmstat

Vmstat reports statistics about processes, Virtual memory, paging activity, faults, CPU activity and disk transfers.

Syntax:

$ vmstat [interval] [count]

Analysing the report
  • The value of r should not be more than the number of CPUs consistently.
  • If the value in b is high and sy is high then there is a possibility of paging or thrashing.
  • A high fr:sr ratio (1-(fr/sr))*100 indicates performance bottleneck.
  • If cy is greater than 0, then there is a severe memory shortage. Increase the RAM.
  • If cs is too high then it indicates a performance problem. Tune time slices with schedo.
  • If us + sy is greater than 80, it is CPU bound.
  • If wa is high when id is not 0, tune I/O.

Thanks

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