Re: CVS commit: src/sys/kern

[Matt Thomas <matt%3am-software.com@localhost>]

> Thinking about SMP, both CURCPU() and curlwp could be the register - with the
> other being indirected from it.  I wonder which it used most?
> curproc should be readable from either.

Some MIPS CPUs have "OS Scratch" registers.  I use one to store curcpu since 
that is the one most useful in the exception handler.

I just made the changes so that PowerPC kernels will keep curlwp in %r13  (I 
choose r13 over r2 because r2 is used for TOC in the PPC64 ABI).  It has 
allowed me to remove several loads of curlwp in the assembly code let alone how 
many references in C code.

   text    data     bss     dec     hex filename
6652040 3805600  212056 10669696         a2ce80 before
6642116 3805600  212056 10659772         a2a7bc after

That's nearly a reduction of 64KB.  The loading of %r13 with curlwp is free 
since in all cases, curlwp would have eventually been loaded into a register at 
some point.