Windows / cpu_times(): return also dpc and interrupt time

[giampaolo]

SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION structure provides DPC time and interrupt time:

typedef struct {
    LARGE_INTEGER IdleTime;
    LARGE_INTEGER KernelTime;
    LARGE_INTEGER UserTime;
    LARGE_INTEGER DpcTime;
    LARGE_INTEGER InterruptTime;
    ULONG InterruptCount;
} _SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION;

This is retrievable via NtQuerySystemInformation which is currently used for per_cpu_times() but not for cpu_times() which uses GetSystemTimes which does not provide these two metrics. cpu_times() may change in order to use NtQuerySystemInformation and extend the namedutple with the new values.

[giampaolo]

@wj32 in your opinion should interrupt and dpc times be excluded when calculating system-wide cpu percent? With this new feature the "busy time" is now calculated like this:

times_all = user + system + idle + interrupt + dpc
times_busy = times_all - idle

I wonder if this is correct.