Date: Mon, 31 Jan 2005 09:02:42 -0600 From: Ryan Sommers <ryans@gamersimpact.com> To: security@revolutionsp.com Cc: freebsd-hackers@freebsd.org Subject: Re: Simple question about CPUs and processes Message-ID: <41FE4892.1050004@gamersimpact.com> In-Reply-To: <51547.81.84.175.77.1107182494.squirrel@81.84.175.77> References: <51547.81.84.175.77.1107182494.squirrel@81.84.175.77>
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security@revolutionsp.com wrote: > Hi list, > > I'd like some insight on the following; Me and a friend were discussing > tech stuff and he said that, when using dual (or more) CPU systems, it is > the hardware itself (and alone) choosing which CPU will execute this or > that process. The OS and the OS alone chooses which processes to migrate (move from one CPU to the other), which process to execute, and all that. This is pretty much the entire job of the scheduler. All the CPU cares about is endlessly executing instructions fed to it and delivering interrupts/exceptions. What your friend might be confusing is the fact that the CPU can receive an interrupt or exception and the CPU will then begin executing the handler for that situation. This does not mean it is choosing which process to execute though. The handler might then make the decision to perform a context switch (switch the executing process). There are a great many sources on the web on topics like these. -- Ryan Sommers ryans@gamersimpact.com
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