Messages in this thread | | | Subject | Re: Guaranteeing processing speed... | Date | Wed, 13 Oct 1999 15:26:06 +0200 (MEST) | From | (Rogier Wolff) |
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David Woodhouse wrote: > > R.E.Wolff@BitWizard.nl said: > > Well, having an application request how much bogomips are available, > > and then tell the OS how much bogomips it will need is also less than > > ideal. The MPEG player will need to know the number of mpeg-mips and > > not bogo-mips. > > The OS would have to deal in time, not *mips of any kind. It's up to the app > to calibrate the speed required for whatever it happens to be doing, and take > into account any variation which it might experience.
So, setting the program to a high RT priority, and then calibrating is going to give the same results as when the OS tells the app that it can take 50% of the CPU.
Note that this won't work "fine". If there is nothing "realtime" running, and I ask the OS: what percentage of the CPU do you have available? I'm going to get the answer: "100%". If I then use (close to) 100%, the X server for instance will be starved. Kind of useless mpeg player then. So the developer decides that if the OS says 100%, he will request 90%. Fine. Now someone else has a system where the X server requires significantly more CPU horsepower to display the same stream. Now what?
Conclusion: The "ask the OS for a guaranteed percentage of the CPU" sysstem isn't all that easy to use anyway....
Roger.
-- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 ** *-- BitWizard writes Linux device drivers for any device you may have! --* ------ Microsoft SELLS you Windows, Linux GIVES you the whole house ------
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