Sticky text

[Howard Chu <howard@harry.lloyd.com>]

This is what I originally wanted for shared-text programs under MiNT, but kept
forgetting to take that last step. With this patch, shared-text memory regions
stay in memory even after the last process using the region exits. That way
the region can be used again if the same program is rerun in the future, saving
load time. Unattached shared-text regions are reclaimed in get_region when
memory is running low, so the overall impact shouldn't cause you to run out
of memory any more often than before.

This patch goes a long way toward making my pre-loaded RAMdisk /bin obsolete.
GCC compiles go a lot faster too, but then, I've got spare RAM to throw at it.
  -- Howard

--- 1.2	1994/03/02 08:06:50
+++ mem.c	1994/04/27 02:18:44
@@ -577,5 +577,5 @@
 	int mode;
 {
-	MEMREGION *m, *n;
+	MEMREGION *m, *n, *s;
 
 	TRACELOW(("get_region(%s,%lx,%x)",
@@ -591,7 +591,6 @@
 	size = ROUND(size);
 
-	n = *map;
-
 	sanity_check(map);
+
 /* exact matches are likely to be rare, so we pre-allocate a new
  * region here; this helps us to avoid re-entrancy problems
@@ -600,4 +599,11 @@
 	m = new_region();
 
+/* We come back and try again if we found and freed any unattached shared
+ * text regions.
+ */
+retry:
+	s = NULL;
+
+	n = *map;
 	while (n) {
 		if (ISFREE(n)) {
@@ -623,8 +629,21 @@
 				}
 			}
+/* If this is an unattached shared text region, leave it as a last resort */
+		} else if (n->links == 0xffff && (n->mflags & M_SHTEXT)) {
+			if (!s)
+				s = n;
 		}
 		n = n->next;
 	}
 
+/* Looks like we're out of free memory. Try freeing an unattached shared text
+ * region, and then try again to fill this request.
+ */
+	if (s) {
+		s->links = 0;
+		free_region(s);
+		goto retry;
+	}
+		
 	if (m)
 		dispose_region(m);
@@ -1295,4 +1314,8 @@
 		{
 			m = s->text;
+/* Kludge for unattached shared region */
+			if (m->links == 0xffff)
+				m->links = 0;
+
 			if (attach_region(curproc, m)) {
 TRACE(("re-using shared text region %lx", m));
--- 1.3	1994/05/05 18:04:18
+++ dosmem.c	1994/04/27 02:13:44
@@ -832,6 +832,12 @@
 				}
 				m->links--;
+/* Leave shared text regions in memory, get_region will reclaim them if
+   memory runs low. Assume that we will never have 65535 processes
+   using a particular memory region. */
 				if (m->links == 0) {
-					free_region(m);
+					if (m->mflags & M_SHTEXT)
+						m->links = 0xffff;
+					else
+						free_region(m);
 				}
 			}