User:Fostermarkd/Performance Troubleshooting
From ConShell
Useful commands for investigating & improving system performance problems.
Contents |
Linux
atop
atop - AT Computing’s System & Process Monitor
This utility is far more feature rich than plain top.
top
- Press '1' to see all CPUs.
- Press 'c' to view full command lines.
- Press 'H' show threads
- Press 'r' renice a process (e.g. -19 to boost it's priority in the scheduler)
vmstat
vmstat 5
Watch for high numbers in these columns
- procs/b - blocked processes, anything more than 0 is bad (why?)
- cpu/wa - wait indicates system is I/O bound
- system/cs - context switches, system is CPU bound... to many processes. Consider tickless or kernel divider options?
iostat
iostat comes with the sysstat package. the await and %util numbers from iostat -x are probably the best indicators as to how a disk is doing
iostat -dx 3
Another interesting command that lets you see I/O to all devices at once & over time is
watch iostat -p ALL
FreeBSD
FreeBSD also has top, ps, vmstat and iostat. However there can be subtle to significant differences in the output and usage.
iostat -h 5
tty ad0 cpu
tin tout KB/t tps MB/s us ni sy in id
0 7 22.01 3 0.07 1 0 1 0 99
0 18 27.20 4 0.11 0 0 1 1 98
0 56 64.00 0 0.02 2 0 1 0 97
0 6 26.74 3 0.07 1 0 1 1 97
0 6 0.00 0 0.00 1 0 1 1 98
