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-rw-r--r--include/linux/idr.h9
1 files changed, 4 insertions, 5 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h
index 1eb755f77f2f..3c01b89aed67 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -18,12 +18,11 @@
#include <linux/rcupdate.h>
/*
- * We want shallower trees and thus more bits covered at each layer. 8
- * bits gives us large enough first layer for most use cases and maximum
- * tree depth of 4. Each idr_layer is slightly larger than 2k on 64bit and
- * 1k on 32bit.
+ * Using 6 bits at each layer allows us to allocate 7 layers out of each page.
+ * 8 bits only gave us 3 layers out of every pair of pages, which is less
+ * efficient except for trees with a largest element between 192-255 inclusive.
*/
-#define IDR_BITS 8
+#define IDR_BITS 6
#define IDR_SIZE (1 << IDR_BITS)
#define IDR_MASK ((1 << IDR_BITS)-1)