Tread/Task IDs

[karlm]

What was the rationelle for not using a full 64-bit thread/task ID on
both 32- and 64-bit systems?  How large would the performance hit be?
Surely at least a full macine register for the task ID was considered
for the X.2 API.  Why was it rejected?  I assume it has to do with not
wanting multi-level thread ID tables for performence reasons.  How
large would the performence hit be?

I admit I have only dabbled in kernel space and I usually do cryptographic
stuff in userspace with 128-bit or 256-bit IDs.  Maybe I'm just jaded from
huge IDs.  However, it would seem to me that there would be many fewer hacks
if IDs were at least 32-bits, if not 64-bits.

I'm sure the X.2 API was very well thought out, I'm just a little surprised
at the kludges HURD is forced to consider due to the L4 API.  I'd like to
see what I'm missing.


-Karl -- ignorant userspace coder