.net - How to get accurate CPU usage for a process on a multi-processor / multi-core system -

or maybe question more "what doing blatantly wrong here?"

i have test app nothing watch own cpu usage. looks little this:

protected performancetrace() {    process currentprocess = process.getcurrentprocess();    this.cpucounter = new performancecounter("process", "% processor time", currentprocess.processname);    this.corecount = environment.processorcount; }  private int corecount; private datetime lastcpuread = datetime.minvalue; private float _cpuusage; private float cpuusage {       {       if ((datetime.now - this.lastcpuread) > timespan.fromseconds(1.0))       {          this._cpuusage = this.cpucounter.nextvalue();       }       return this._cpuusage / this.corecount;    } } 

the cpuusage property read frequently. here's thing:

on machine, environment.processorcount produces value of 2. however, value coming counter 800. assuming has multiple cores , hyperthreading. can actual value i'm looking for? (the total % processor time particular process)

you rigt - have divide number performance counters number of cpus times number of real threads per cpu - 1 per core, plus 1 per core if hyperthreading factor.

in c# don't know how determine this. in native code can use getlogicalprocessorinformation , its associated structure count logical processors, including share core.