From 050a6b47d98e2bcea909c1129111e721668aaa2c Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 27 Feb 2013 17:05:06 -0800 Subject: [PATCH] idr: make idr_layer larger With recent preloading changes, idr no longer keeps full layer cache per each idr instance (used to be ~6.5k per idr on 64bit) and the previous patch removed restriction on the bitmap size. Both now allow us to have larger layers. Increase IDR_BITS to 8 regardless of BITS_PER_LONG. Each layer is slightly larger than 2k on 64bit and 1k on 32bit and carries 256 entries. The size isn't too large, especially compared to what we used to waste on per-idr caches, and 256 entries should be able to serve most use cases with single layer. The max tree depth is 4 which is much better than the previous 6 on 64bit and 7 on 32bit. Signed-off-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/idr.h | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/include/linux/idr.h b/include/linux/idr.h index 63aa542da49..43b87b1c77a 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -17,14 +17,13 @@ #include #include -#if BITS_PER_LONG == 32 -# define IDR_BITS 5 -#elif BITS_PER_LONG == 64 -# define IDR_BITS 6 -#else -# error "BITS_PER_LONG is not 32 or 64" -#endif - +/* + * 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. + */ +#define IDR_BITS 8 #define IDR_SIZE (1 << IDR_BITS) #define IDR_MASK ((1 << IDR_BITS)-1) -- 2.20.1