From 255497dd01ac11f849988e7901a0d83d4e4a9d58 Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Wed, 1 Feb 2006 03:05:26 -0800 Subject: [PATCH] --- yaml --- r: 19365 b: refs/heads/master c: 79046ae07ae21245520ca0aab985ee6678a879f8 h: refs/heads/master i: 19363: 2cfc5998fe368129083c9e12202b7a7034a53e0f v: v3 --- [refs] | 2 +- trunk/include/linux/mmzone.h | 8 ++++++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/[refs] b/[refs] index 5a730d9d9e76..900cdbb5661b 100644 --- a/[refs] +++ b/[refs] @@ -1,2 +1,2 @@ --- -refs/heads/master: 42c722d4cb4022e56ff200f3f5a58c0dfd7edac6 +refs/heads/master: 79046ae07ae21245520ca0aab985ee6678a879f8 diff --git a/trunk/include/linux/mmzone.h b/trunk/include/linux/mmzone.h index 93a849f742db..88c30f844abf 100644 --- a/trunk/include/linux/mmzone.h +++ b/trunk/include/linux/mmzone.h @@ -91,6 +91,14 @@ struct per_cpu_pageset { * be 8 (2 ** 3) zonelists. GFP_ZONETYPES defines the number of possible * combinations of zone modifiers in "zone modifier space". * + * As an optimisation any zone modifier bits which are only valid when + * no other zone modifier bits are set (loners) should be placed in + * the highest order bits of this field. This allows us to reduce the + * extent of the zonelists thus saving space. For example in the case + * of three zone modifier bits, we could require up to eight zonelists. + * If the left most zone modifier is a "loner" then the highest valid + * zonelist would be four allowing us to allocate only five zonelists. + * * NOTE! Make sure this matches the zones in */ #define GFP_ZONEMASK 0x07