Thread Switching Overhead

I was reading a post by Sue Loh today. It gives a very cool insight into some threading problems with an expedited thread quantum on CE. Essentially, since threads have half the time to do their actual work, the thread context switching overhead percentage provides a bigger hit on performance. Putting this in a real-world situation , I state it like this. I am currently driving 1.5 hours to work and back (each way) so I spend a tremendous amount of time on the road. Of course, I put in 9 hour days or so. Most people feel this is a lot of distance to drive, and I agree (hense why I’m moving to Greenville, SC this weekend). However, imagine if I had to drive to work in the morning, put in 4 or 5 hours of work, then drive home and back and put in another 4 or 5 hours of work. I’d be spending just about as much time going back and forth to work as I did actually working. This is the same problem with the expedited thread quantum. Sue sites the difference of 100 milliseconds that is set by default in CE to 50 miliseconds that an OEM might change this value to. Keep in mind that if you change the amount of work that can be done in a single pass, there is some overhead in the context switching that will be much more evident with the actual work cycles being truncated.

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