From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lai Jiangshan Subject: [RFC PATCH 01/23 V2] node_states: introduce N_MEMORY Date: Thu, 2 Aug 2012 10:52:49 +0800 Message-ID: <1343875991-7533-2-git-send-email-laijs@cn.fujitsu.com> References: <1343875991-7533-1-git-send-email-laijs@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1343875991-7533-1-git-send-email-laijs-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Mel Gorman Cc: Christoph Lameter , Jiri Kosina , Dan Magenheimer , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Michal Hocko , Paul Gortmaker , Konstantin Khlebnikov , "H. Peter Anvin" , Sam Ravnborg , Gavin Shan , Rik van Riel , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Hugh Dickins , Ingo Molnar , Mel Gorman , KOSAKI Motohiro , David Rientjes , Petr Holasek , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Wanlong Gao , Djalal Harouni , Rusty Russell , Wen Congyang , Peter Zijlstra List-Id: linux-mm.kvack.org We have N_NORMAL_MEMORY for standing for the nodes that have normal memory with zone_type <= ZONE_NORMAL. And we have N_HIGH_MEMORY for standing for the nodes that have normal or high memory. But we don't have any word to stand for the nodes that have *any* memory. And we have N_CPU but without N_MEMORY. Current code reuse the N_HIGH_MEMORY for this purpose because any node which has memory must have high memory or normal memory currently. A) But this reusing is bad for *readability*. Because the name N_HIGH_MEMORY just stands for high or normal: A.example 1) mem_cgroup_nr_lru_pages(): for_each_node_state(nid, N_HIGH_MEMORY) The user will be confused(why this function just counts for high or normal memory node? does it counts for ZONE_MOVABLE's lru pages?) until someone else tell them N_HIGH_MEMORY is reused to stand for nodes that have any memory. A.cont) If we introduce N_MEMORY, we can reduce this confusing AND make the code more clearly: A.example 2) mm/page_cgroup.c use N_HIGH_MEMORY twice: One is in page_cgroup_init(void): for_each_node_state(nid, N_HIGH_MEMORY) { It means if the node have memory, we will allocate page_cgroup map for the node. We should use N_MEMORY instead here to gaim more clearly. The second using is in alloc_page_cgroup(): if (node_state(nid, N_HIGH_MEMORY)) addr = vzalloc_node(size, nid); It means if the node has high or normal memory that can be allocated from kernel. We should keep N_HIGH_MEMORY here, and it will be better if the "any memory" semantic of N_HIGH_MEMORY is removed. B) This reusing is out-dated if we introduce MOVABLE-dedicated node. The MOVABLE-dedicated node should not appear in node_stats[N_HIGH_MEMORY] nor node_stats[N_NORMAL_MEMORY], because MOVABLE-dedicated node has no high or normal memory. In x86_64, N_HIGH_MEMORY=N_NORMAL_MEMORY, if a MOVABLE-dedicated node is in node_stats[N_HIGH_MEMORY], it is also means it is in node_stats[N_NORMAL_MEMORY], it causes SLUB wrong. The slub uses for_each_node_state(nid, N_NORMAL_MEMORY) and creates kmem_cache_node for MOVABLE-dedicated node and cause problem. In one word, we need a N_MEMORY. We just intrude it as an alias to N_HIGH_MEMORY and fix all im-proper usages of N_HIGH_MEMORY in late patches. Signed-off-by: Lai Jiangshan --- include/linux/nodemask.h | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h index 7afc363..c6ebdc9 100644 --- a/include/linux/nodemask.h +++ b/include/linux/nodemask.h @@ -380,6 +380,7 @@ enum node_states { #else N_HIGH_MEMORY = N_NORMAL_MEMORY, #endif + N_MEMORY = N_HIGH_MEMORY, N_CPU, /* The node has one or more cpus */ NR_NODE_STATES }; -- 1.7.1