CODEWITHSUNDEEP
c++windowsoperating-systemsystem-calls
user3811839
user3811839

Reputation: 141

windows system call

On Linux it seems getpid() is the simplest system call to invoke to best-measure the time taken for a system call. Would somebody be able to refer me to a simple windows system call I could make to measure the time spent changing to kernel mode and back please?

I did google and found a list of Windows System calls on MSDN website, but they all referred to opening files- which seemed strange:

http://msdn.microsoft.com/en-us/library/t0wd4t32.aspx

I am on Windows 7 64 bit.

Upvotes: 2

Views: 1011

Answers (1)

user541686
user541686

Reputation: 210755

My suggestion (and this is just based on intuition) is to try something like

CloseHandle(NULL)

or

WaitForMultipleObjectsEx(0, NULL, 0, 0, FALSE)

on the grounds that it should be a no-op. However, I don't have any evidence to support this.

Update

A little benchmarking on Win8.1 x64 shows the (undocumented) NtDisplayString(NULL) function is even faster, followed by the semi-documented NtAllocateLocallyUniqueId(&some_luid). You'll have to dynamically load them from NTDLL using GetProcAddress; the signatures are:

NTSTATUS NTAPI PNtAllocateLocallyUniqueId(PLUID LUID);
NTSTATUS NTAPI PNtDisplayString(PUNICODE_STRING DisplayString);

Upvotes: 1

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