Win32 Thread scheduling

Question

As I understand, windows thread scheduler does not discriminate beween threads belonging two different processes, provided all of them have the same base priority. My questi

Answer 1

That depends on the behavior of the threads. In general with a 50 : 1 difference in thread count, yes, the application with more threads is going to get a lot more time. However, windows also uses dynamic thread prioritization, which can change this somewhat. Dynamic thread prioritization is described here:

http://support.microsoft.com/kb/109228

Relevant excerpt:

The base priority of a thread is the base level from which these upward adjustments are made. The current priority of a thread is called its dynamic priority. Interactive threads that yield before their time slice is up will tend to be adjusted upward in priority from their base priority. Compute-bound threads that do not yield, consuming their entire time slice, will tend to have their priority decreased, but not below the base level. This arrangement is often called heuristic scheduling. It provides better interactive performance and tends to lessen the system impact of "CPU hog" threads.