From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx199.postini.com [74.125.245.199]) by kanga.kvack.org (Postfix) with SMTP id CCF8D6B005D for ; Fri, 17 Aug 2012 10:09:22 -0400 (EDT) Date: Fri, 17 Aug 2012 14:09:21 +0000 From: Christoph Lameter Subject: Re: [PATCH V2] mm: introduce N_LRU_MEMORY to distinguish between normal and movable memory In-Reply-To: <502DA342.7020005@huawei.com> Message-ID: <0000013934eaad61-2dad9ff0-e671-4155-98d3-501f243caaba-000000@email.amazonses.com> References: <502CA44C.80901@huawei.com> <502DA342.7020005@huawei.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Hanjun Guo Cc: Wu Jianguo , Jiang Liu , Tony Luck , Pekka Enberg , Matt Mackall , Mel Gorman , Yinghai Lu , KAMEZAWA Hiroyuki , KOSAKI Motohiro , David Rientjes , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jiang Liu , qiuxishi On Fri, 17 Aug 2012, Hanjun Guo wrote: > N_NORMAL_MEMORY means non-LRU page allocs possible. Hmmm... It may be better to say N_NORMAL_MEMORY Allocations are allowed for pages that will not be managed via a LRU and that cannot be moved by the page migration logic. N_LRU_MEMORY Allocations are possible for pages that are managed via LRUs N_HIGH_MEMORY Allocations are allowed for pages that are only temporarliy mapped into kernel address space. Any node that has the ability to allocate memory at all has at least N_LRU_MEMORY set. > > /* > * Bitmasks that are kept for all the nodes. > + * N_NORMAL_MEMORY means non-LRU page allocs possible. > + * N_LRU_MEMORY means LRU page allocs possible, > + * node with ZONE_DMA/ZONE_DMA32/ZONE_NORMAL is marked with > + * N_LRU_MEMORY and N_NORMAL_MEMORY, > + * node with ZONE_MOVABLE is *only* marked with N_LRU_MEMORY, > + * node with ZONE_HIGHMEM is marked with N_LRU_MEMORY and N_HIGH_MEMORY. > + * N_LRU_MEMORY also means node has any regular memory. > */ > enum node_states { > N_POSSIBLE, /* The node could become online at some point */ > N_ONLINE, /* The node is online */ > - N_NORMAL_MEMORY, /* The node has regular memory */ > + N_NORMAL_MEMORY, /* The node has normal memory */ > + N_LRU_MEMORY, /* The node has regular memory */ These comments are utter garbage and just repeat what the constant alreadty expresses. . Please actually say something meaningful that another developer can use when he attempts to understand what these bits mean. -- 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