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authorNick Piggin <nickpiggin@yahoo.com.au>2005-11-13 16:06:45 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-13 18:14:12 -0800
commit669ed17521b9b78cdbeac8a53c30599aca9527ce (patch)
tree9a4c037120b7a85943c37115be9f4a6eacb28874 /mm/page_alloc.c
parent2d6c666e8704cf06267f29a4fa3d2cf823469c38 (diff)
[PATCH] mm: highmem watermarks
The pages_high - pages_low and pages_low - pages_min deltas are the asynch reclaim watermarks. As such, the should be in the same ratios as any other zone for highmem zones. It is the pages_min - 0 delta which is the PF_MEMALLOC reserve, and this is the region that isn't very useful for highmem. This patch ensures highmem systems have similar characteristics as non highmem ones with the same amount of memory, and also that highmem zones get similar reclaim pressures to other zones. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c27
1 files changed, 14 insertions, 13 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 845b91749a4..3c5cf664abd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2397,13 +2397,18 @@ void setup_per_zone_pages_min(void)
}
for_each_zone(zone) {
+ unsigned long tmp;
spin_lock_irqsave(&zone->lru_lock, flags);
+ tmp = (pages_min * zone->present_pages) / lowmem_pages;
if (is_highmem(zone)) {
/*
- * Often, highmem doesn't need to reserve any pages.
- * But the pages_min/low/high values are also used for
- * batching up page reclaim activity so we need a
- * decent value here.
+ * __GFP_HIGH and PF_MEMALLOC allocations usually don't
+ * need highmem pages, so cap pages_min to a small
+ * value here.
+ *
+ * The (pages_high-pages_low) and (pages_low-pages_min)
+ * deltas controls asynch page reclaim, and so should
+ * not be capped for highmem.
*/
int min_pages;
@@ -2414,19 +2419,15 @@ void setup_per_zone_pages_min(void)
min_pages = 128;
zone->pages_min = min_pages;
} else {
- /* if it's a lowmem zone, reserve a number of pages
+ /*
+ * If it's a lowmem zone, reserve a number of pages
* proportionate to the zone's size.
*/
- zone->pages_min = (pages_min * zone->present_pages) /
- lowmem_pages;
+ zone->pages_min = tmp;
}
- /*
- * When interpreting these watermarks, just keep in mind that:
- * zone->pages_min == (zone->pages_min * 4) / 4;
- */
- zone->pages_low = (zone->pages_min * 5) / 4;
- zone->pages_high = (zone->pages_min * 6) / 4;
+ zone->pages_low = zone->pages_min + tmp / 4;
+ zone->pages_high = zone->pages_min + tmp / 2;
spin_unlock_irqrestore(&zone->lru_lock, flags);
}
}