Red Hat Enterprise Linux 5 Administration Unleashed

414CHAPTER 20Monitoring System ResourcesUnder the swap header:sisoAmount of memory swapped in from the diskAmount of memory swapped to the diskUnder the io header:biboNumber of blocks received from a block deviceNumber of blocks sent to a block deviceUnder the system header:incsNumber of interrupts per secondNumber of context switches per secondUnder the cpu header:ussyidwastPercentage of time the processor(s) spent running non-kernel codePercentage of time the processor(s) spent running kernel codePercentage of time spent not running any codePercentage of time spent waiting for I/OPercentage of time the processor(s) spent running kernel codeJust like free, the content displayed by vmstat is a snapshot. To generate output atspecific intervals, use the command vmstat , where is the amountof delay, in seconds, between output. To stop the continuous output, press Ctrl+C.To specify the number of intervals, use the format vmstat . Forexample, vmstat 60 5 produces statistics every 60 seconds for 5 iterations and then stops.TIPAnother great argument to vmstat is -s. vmstat -s outputs a quick summary of thesystem’s memory as shown in Listing 20.10.LISTING 20.10 Example output from vmstat -s514188 total memory491292 used memory327068 active memory105080 inactive memory22896 free memory14444 buffer memory192768 swap cache522104 total swap224240 used swap