Module Name:	syssrc
Committed By:	thorpej
Date:		Tue Aug 15 05:21:22 UTC 2000

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

Log Message:
- Make lazy I-sync a little safer -- always mark the pmap as needing
  I-sync in pmap_remove_mapping() if the old mapping had PG_EXEC, and
  kick curcpu (IMB) or other CPUs (via an IPI) only if the pmap was
  the kernel pmap or active on other CPUs (curcpu is handled in userret()).
- Use lazy I-sync everywhere, (hopefully) eliminating the last of the
  I-sync issues for multiprocessor support.
- Eliminate some memory barriers added in a couple of previous revisions,
  after some discussion on port-alpha/tech-smp.

Still some lazy I-sync optimization possibilites:
- pmap_changebit() does not need to I-sync when only write-protecting
  a page.
- pmap_asn_alloc() may be able to cancel a pending lazy I-sync when a
  new ASN is allocated.  Need to double check against Green Book or
  Brown Book.


To generate a diff of this commit:
cvs rdiff -r1.141 -r1.142 syssrc/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.