Tuesday, August 28, 2012

Top Counters in Windows Perfmon

 

Bottleneck analysis

  • Processor utilization
    • System\Processor Queue Length - number of threads queued and waiting for time on the CPU. Divide this by the number of CPUs in the system. If the answer is less than 10, the system is most likely running well.
  • Memory utilization
    • Memory\Pages Input/Sec - The best indicator of whether you are memory-bound, this counter shows the rate at which pages are read from disk to resolve hard page faults. In other words, the number of times the system was forced to retrieve something from disk that should have been in RAM. Occasional spikes are fine, but this should generally flat line at zero.
  • Disk Utilization
    • PhysicalDisk\Current Disk Queue Length\driveletter - this is probably the single most valuable counter to watch. It shows how many read or write requests are waiting to execute to the disk. For single disks, it should idle at 2-3 or lower, with occasional spikes being okay. For RAID arrays, divide by the number of active spindles in the array; again try for 2-3 or lower. Because a shortage of RAM will tend to beat on the disk, look closely at the Memory\Pages Input/Sec counter if disk queue lengths are high.
  • Network Utilization
    • Network Interface\Output Queue Length\nic name - is the number of packets in queue waiting to be sent. If there is a sustained average of more than two packets in queue, you should be looking to resolve a network bottleneck.
    • Network Interface\Packets Received Errors\nic name - packet errors that kept the TCP/IP stack from delivering packets to higher layers. This value should stay low.

General activity counters

  • Processor utilization
    • Processor\% Processor Time\_Total - just a handy idea of how 'loaded' the CPU is at any given time. Don't confuse 100% processor utilization with a slow system though - processor queue length, mentioned above, is much better at determining this.
  • Memory utilization
    • Process\Working Set\_Total (or per specific process) - this basically shows how much memory is in the working set, or currently allocated RAM.
    • Memory\Available MBytes - amount of free RAM available to be used by new processes.
  • Disk Utilization
    • PhysicalDisk\Bytes/sec\_Total (or per process) - shows the number of bytes per second being written to or read from the disk.
  • Network Utilization
    • Network Interface\Bytes Total/Sec\nic name - Measures the number of bytes sent or received.

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