Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759906Ab2J2PsU (ORCPT ); Mon, 29 Oct 2012 11:48:20 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:56602 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1759690Ab2J2PsP (ORCPT ); Mon, 29 Oct 2012 11:48:15 -0400 X-IronPort-AV: E=Sophos;i="4.80,673,1344182400"; d="scan'208";a="6093338" From: Lai Jiangshan To: Mel Gorman , David Rientjes , LKML , x86 maintainers Cc: Jiang Liu , Rusty Russell , Yinghai Lu , KAMEZAWA Hiroyuki , Yasuaki ISIMATU , Andrew Morton , Lai Jiangshan , Christoph Lameter , Hillf Danton Subject: [V5 PATCH 05/26] node_states: introduce N_MEMORY Date: Mon, 29 Oct 2012 23:20:55 +0800 Message-Id: <1351524078-20363-4-git-send-email-laijs@cn.fujitsu.com> X-Mailer: git-send-email 1.7.4.4 In-Reply-To: <1351523301-20048-1-git-send-email-laijs@cn.fujitsu.com> References: <1351523301-20048-1-git-send-email-laijs@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/10/29 23:18:54, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/10/29 23:18:58, Serialize complete at 2012/10/29 23:18:58 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3103 Lines: 87 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 Acked-by: Christoph Lameter Acked-by: Hillf Danton --- 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 }; -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/