Linux, performance analysis
How to monitor resources and their usage
The availability of CPU and memory resources can be found in
/proc/cpuinfo
/proc/meminfo
and their usage can be monitored using
top
vmstat
Users tend to care most about the %CPU time of top which is indeed important if many processes are asking for cpu-cycles.
But systems really get stalled by what is not reflected by %CPU: shortage of memory, causing the system to spend more time on exchanging memory with diskspace than actually running the jobs. This is indicated by vmstat as high values for
- si so bi bo : exchanging memory
- wa : waiting for I/O
The jobs with the highest amount of RESident memory contribute most to the memory exchange. They can be brought to the fore in top using the commands
F (Select sort field)
q (to be the Resident size)
If your desktop shows marks of memory shortage, consider reverting to a remote compute server. On those running Linux (most of them do), you may wish view only your own processes in top:
u (Show specific user only)
youraccount