Re: 2.4 and 2GB swap partition limit

From: David S. Miller (davem@redhat.com)
Date: Tue May 01 2001 - 19:34:28 EST


Rik van Riel writes:
> Then we will be scanning through memory looking for something to
> swap out (otherwise we'd not be in need of swap space, right?).
> At this point we can simply free up swap entries while scanning
> through memory looking for stuff to swap out.

Sounds a lot like my patch I posted a few weeks ago:

--- mm/vmscan.c.~1~ Wed Apr 11 19:05:59 2001
+++ mm/vmscan.c Thu Apr 12 17:19:51 2001
@@ -441,8 +441,14 @@
         maxscan = nr_inactive_dirty_pages;
         while ((page_lru = inactive_dirty_list.prev) != &inactive_dirty_list &&
                                 maxscan-- > 0) {
+ int dead_swap_page;
+
                 page = list_entry(page_lru, struct page, lru);
 
+ dead_swap_page =
+ (PageSwapCache(page) &&
+ page_count(page) == (1 + !!page->buffers));
+
                 /* Wrong page on list?! (list corruption, should not happen) */
                 if (!PageInactiveDirty(page)) {
                         printk("VM: page_launder, wrong page on list.\n");
@@ -453,9 +459,10 @@
                 }
 
                 /* Page is or was in use? Move it to the active list. */
- if (PageTestandClearReferenced(page) || page->age > 0 ||
- (!page->buffers && page_count(page) > 1) ||
- page_ramdisk(page)) {
+ if (!dead_swap_page &&
+ (PageTestandClearReferenced(page) || page->age > 0 ||
+ (!page->buffers && page_count(page) > 1) ||
+ page_ramdisk(page))) {
                         del_page_from_inactive_dirty_list(page);
                         add_page_to_active_list(page);
                         continue;
@@ -481,8 +488,11 @@
                         if (!writepage)
                                 goto page_active;
 
- /* First time through? Move it to the back of the list */
- if (!launder_loop) {
+ /* First time through? Move it to the back of the list,
+ * but not if it is a dead swap page. We want to reap
+ * those as fast as possible.
+ */
+ if (!launder_loop && !dead_swap_page) {
                                 list_del(page_lru);
                                 list_add(page_lru, &inactive_dirty_list);
                                 UnlockPage(page);
-
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This archive was generated by hypermail 2b29 : Mon May 07 2001 - 21:00:11 EST