>>> Olivier Galibert <[EMAIL PROTECTED]> 20-Jun-00 11:27:41 PM >>>
>Bzzt wrong. Going userspace->kernel and back does
>not involve any context switch. It's going userspace->
>another userspace that does.
Bzzt. Not quite right.
userspace -> userspace doesn't happen does it?
it goes userspace -> kernel -> userspace
with the last userspace being the driver. The kernel has to get
involved to work out which driver is required.
But the context switching argument is not at the heart of the
microkernel problem because calls can be optimized out... some people
also suggest that the better modularity reduces the need for context
switches and therefore saves over time.
AFAIK the context switching argument (generally) is a pretty
subjective one. However, I'm no HURD expert. How it works in practice
on the HURD might mean that context switches are a pain... but I'm not
sure what you compare it to since the HURD is so immature.
Nic
