Split Capabilities: Making Capabilities Scale

[Jonathan S. Shapiro]

> In KeyKOS we limited the maximum update rate for the version number to the
> rate of disk I/O.  We used a 32 bit counter.  Because relevant disk writes
> only occurred at the checkpoint rate (about once every 5 minutes), that is
> some 40,000+ years.  (I think there was one kernel capability which would
> allow the rate to be at CPU speeds rather than checkpoint speeds.  But as
I
> remember, that capability was not widely distributed.)

This is an important optimization, and one that EROS implements in a minor
variation. I wanted to get the idea clear before optimizing it away. :-)

shap