2.4.0-test11

 Documentation

diff -u --recursive --new-file v2.4.0-test10/linux/Documentation/cachetlb.txt linux/Documentation/cachetlb.txt
--- v2.4.0-test10/linux/Documentation/cachetlb.txt   Tue Oct 31 12:42:25 2000
+++ linux/Documentation/cachetlb.txt   Thu Nov  9 15:57:40 2000
@@ -305,19 +305,23 @@
    If D-cache aliasing is not an issue, this routine may
    simply be defined as a nop on that architecture.
 
-        TODO: If we set aside a few bits in page->flags as
-         "architecture private", these interfaces could
-         be implemented much more efficiently.  This would
-         allow one to "defer" (perhaps indefinitely) the
-         actual flush if there are currently no user processes
-         mapping this page.
+        There is a bit set aside in page->flags (PG_arch_1) as
+   "architecture private".  The kernel guarentees that,
+   for pagecache pages, it will clear this bit when such
+   a page first enters the pagecache.
 
-         The idea is, first at flush_dcache_page() time, if
-         page->mapping->i_mmap is an empty list, just mark
-         one of the architecture private page flag bits.
-              Later, in update_mmu_cache(), a check could be made
-         of this flag bit, and if set the flush is done
-         and the flag bit is cleared.
+   This allows these interfaces to be implemented much more
+   efficiently.  It allows one to "defer" (perhaps indefinitely)
+   the actual flush if there are currently no user processes
+   mapping this page.  See sparc64's flush_dcache_page and
+   update_mmu_cache implementations for an example of how to go
+   about doing this.
+
+   The idea is, first at flush_dcache_page() time, if
+   page->mapping->i_mmap{,_shared} are empty lists, just mark the
+   architecture private page flag bit.  Later, in
+   update_mmu_cache(), a check is made of this flag bit, and if
+   set the flush is done and the flag bit is cleared.
 
 XXX Not documented: flush_icache_page(), need to talk to Paul
                     Mackerras, David Mosberger-Tang, et al.