Re: Syscalls versus Call Gates
Posted: Fri Feb 13, 2009 10:52 am
Thread necro of the year (so far) award 
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Syscalls versus Call Gates
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Re: Syscalls versus Call Gates
Posted: Fri Feb 13, 2009 3:06 pm
For software isolation, surely array accesses would have to be bounds-checked? Static analysis can only go so far. Wouldn't the time spent bounds checking be far greater than any time saved from the MMU, address space switching, privilege level switching, TLB invalidating and the other reasons mentioned above?
Re: Syscalls versus Call Gates
Posted: Sat Feb 14, 2009 12:14 am
Read section 4.4 of this paper.
In a nutshell, run-time checks add about 4.5% overhead, but for many types of real-world tasks this will be outweighed by the cost of ring transitions, TLB misses, etc.
In a nutshell, run-time checks add about 4.5% overhead, but for many types of real-world tasks this will be outweighed by the cost of ring transitions, TLB misses, etc.
Re: Syscalls versus Call Gates
Posted: Sat Feb 14, 2009 6:35 am
Thank you for the link to the paper, Colonel. I tried downloading various papers from Microsoft's website, but the server just wasn't working. I wonder what server software they're running 