The expensive part is often having to save and restore all the state in registers and other bits on context switch.


On Tue, Jan 5, 2016 at 4:01 PM, Steinar H. Gunderson <sgunderson@bigfoot.com> wrote:
On Tue, Jan 05, 2016 at 03:36:10PM -0600, Benjamin Cronce wrote:
> You can't have different virtual memory space and not take some large
> switching overhead without devoting a lot of transistors to massive caches.
> And the larger the caches, the higher the latency.

I'm sure you already know this, but just to add to what you're saying:
Modern CPUs actually have cache-line tagging tricks so that they don't have
to blow the entire L1 just because you do a context switch. It would be too
expensive.

/* Steinar */
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