CVS commit: src/sys/arch/alpha/alpha

[Jason R Thorpe <thorpej%netbsd.org@localhost>]

Module Name:    src
Committed By:   thorpej
Date:           Tue Jul 26 04:11:54 UTC 2005

Modified Files:
        src/sys/arch/alpha/alpha: pmap.c

Log Message:
1. Disable the lazy allocation of lev1map in pmap_enter(), instead doing
   it in pmap_create(), and freeing the lev1map in pmap_destroy().  This
   means that pm_lev1map is consistent for the life of the pmap.
2. pmap_extract() now uses vtophys() for the kernel pmap.  This avoids
   having to lock the kernel pmap, since kernel PT pages are never freed.
3. Because of (1), pmap_asn_alloc() no longer needs to operate on a locked
   pmap; pm_lev1map will never change over the life of the pmap, and all
   other access to the pmap is done in per-CPU fields or with atomic
   operations.
4. Because of (3), pmap_activate() no longer needs to lock the pmap
   to do its work, thus eliminating the deadlock with sched_lock described
   in PR port-alpha/25599.  This is safe because we are guaranteed that
   the pmap is still alive, since by definition an LWP that uses that it
   is about to run.

Thanks to Michael Hitch for the analysis, and Michael and Ragge for testing.


To generate a diff of this commit:
cvs rdiff -r1.210 -r1.211 src/sys/arch/alpha/alpha/pmap.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.