Messages in this thread | | | Date | Mon, 23 Oct 2000 10:02:04 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | Re: (no subject) |
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On Mon, 23 Oct 2000, Marco wrote:
> Hi, > can someone briefly explain me how the kernel code prevent the > preemption of process executing a system call ? I read several technical > papers but I haven't found (or perhaps don't understood) a response > there. > Many thanks in advance > > Marco Bacchetta >
A system call does not cause a preemption. In Unix/Linux, the system call executes in the context of the user. The only time preemption occurs, as a result of a system call, is when waiting for I/O to complete or some similar resource. In this case, instead of spinning, wasting CPU cycles, the kernel gives the CPU to somebody else who could use it while your I/O is completing.
Cheers, Dick Johnson
Penguin : Linux version 2.2.17 on an i686 machine (801.18 BogoMips).
"Memory is like gasoline. You use it up when you are running. Of course you get it all back when you reboot..."; Actual explanation obtained from the Micro$oft help desk.
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