ixgbe: Cleanup feature setup code to make the code more readable

[pandora-kernel.git] / mm / page_alloc.c

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e2f2699..fe753ec 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2681,6 +2681,7 @@ static void __meminit zone_init_free_lists(struct zone *zone)
 
 static int zone_batchsize(struct zone *zone)
 {
+#ifdef CONFIG_MMU
        int batch;
 
        /*
@@ -2706,9 +2707,26 @@ static int zone_batchsize(struct zone *zone)
         * of pages of one half of the possible page colors
         * and the other with pages of the other colors.
         */
-       batch = (1 << (fls(batch + batch/2)-1)) - 1;
+       batch = rounddown_pow_of_two(batch + batch/2) - 1;
 
        return batch;
+
+#else
+       /* The deferral and batching of frees should be suppressed under NOMMU
+        * conditions.
+        *
+        * The problem is that NOMMU needs to be able to allocate large chunks
+        * of contiguous memory as there's no hardware page translation to
+        * assemble apparent contiguous memory from discontiguous pages.
+        *
+        * Queueing large contiguous runs of pages for batching, however,
+        * causes the pages to actually be freed in smaller chunks.  As there
+        * can be a significant delay between the individual batches being
+        * recycled, this leads to the once large chunks of space being
+        * fragmented and becoming unavailable for high-order allocations.
+        */
+       return 0;
+#endif
 }
 
 static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)