From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 10 May 2007 16:26:49 +0900 From: KAMEZAWA Hiroyuki Subject: [Request-For-Test] [PATCH] change zonelist order v6 [3/3] documentaion Message-Id: <20070510162649.6410c12f.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20070510161611.fe1a696b.kamezawa.hiroyu@jp.fujitsu.com> References: <20070510161611.fe1a696b.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Lee.Schermerhorn@hp.com, apw@shadowen.org, clameter@sgi.com, akpm@linux-foundation.org, ak@suse.de, jbarnes@virtuousgeek.org List-ID: Documentation for numa_zonelist_order. Signed-Off-By: KAMEZAWA Hiroyuki Documentation/kernel-parameters.txt | 5 +++ Documentation/sysctl/vm.txt | 46 ++++++++++++++++++++++++++++++++++++ 2 files changed, 51 insertions(+) Index: linux-2.6.21-mm2/Documentation/sysctl/vm.txt =================================================================== --- linux-2.6.21-mm2.orig/Documentation/sysctl/vm.txt +++ linux-2.6.21-mm2/Documentation/sysctl/vm.txt @@ -33,6 +33,7 @@ Currently, these files are in /proc/sys/ - panic_on_oom - swap_prefetch - stat_interval +- numa_zonelist_order ============================================================== @@ -248,3 +249,48 @@ determines the frequency of these consol The default value is 1 second. +============================================================== + +numa_zonelist_order + +This sysctl is only for NUMA. +'where the memory is allocated from' is controlled by zonelists. +(This documentation ignores ZONE_HIGHMEM/ZONE_DMA32 for simple explanation. + you may be able to read ZONE_DMA as ZONE_DMA32...) + +In non-NUMA case, a zonelist for GFP_KERNEL is ordered as following. +ZONE_NORMAL -> ZONE_DMA +This means that a memory allocation request for GFP_KERNEL will +get memory from ZONE_DMA only when ZONE_NORMAL is not available. + +In NUMA case, you can think of following 2 types of order. +Assume 2 node NUMA and below is zonelist of Node(0)'s GFP_KERNEL + +(A) Node(0) ZONE_NORMAL -> Node(0) ZONE_DMA -> Node(1) ZONE_NORMAL +(B) Node(0) ZONE_NORMAL -> Node(1) ZONE_NORMAL -> Node(0) ZONE_DMA. + +Type(A) offers the best locality for processes on Node(0), but ZONE_DMA +will be used before ZONE_NORMAL exhaustion. This increases possibility of +out-of-memory(OOM) of ZONE_DMA because ZONE_DMA is tend to be small. + +Type(B) cannot offer the best locality but is more robust against OOM of +the DMA zone. + +Type(A) is called as "Node" order. Type (B) is "Zone" order. + +"Node order" orders the zonelists by node, then by zone within each node. +Specify "[Nn]ode" for zone order + +"Zone Order" orders the zonelists by zone type, then by node within each +zone. Specify "[Zz]one"for zode order. + +Specify "[Dd]efault" to request automatic configuration. Autoconfiguration +will select "node" order in following case. +(1) if the DMA zone does not exist or +(2) if the DMA zone comprises greater than 50% of the available memory or +(3) if any node's DMA zone comprises greater than 60% of its local memory and + the amount of local memory is big enough. + +Otherwise, "zone" order will be selected. Default order is recommended unless +this is causing problems for your system/application. + Index: linux-2.6.21-mm2/Documentation/kernel-parameters.txt =================================================================== --- linux-2.6.21-mm2.orig/Documentation/kernel-parameters.txt +++ linux-2.6.21-mm2/Documentation/kernel-parameters.txt @@ -1231,6 +1231,11 @@ and is between 256 and 4096 characters. nowb [ARM] + numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. + one of ['zone', 'node', 'default'] can be specified + This can be set from sysctl after boot. + See Documentation/sysctl/vm.txt for details. + nr_uarts= [SERIAL] maximum number of UARTs to be registered. opl3= [HW,OSS] -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org