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-rw-r--r--mm/page_alloc.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c73dbbc1cd8..08e8627361a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1671,6 +1671,18 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
if (batch < 1)
batch = 1;
+ /*
+ * Clamp the batch to a 2^n - 1 value. Having a power
+ * of 2 value was found to be more likely to have
+ * suboptimal cache aliasing properties in some cases.
+ *
+ * For example if 2 tasks are alternately allocating
+ * batches of pages, one task can end up with a lot
+ * 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;
+
for (cpu = 0; cpu < NR_CPUS; cpu++) {
struct per_cpu_pages *pcp;