From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 15 Sep 2006 10:13:32 -0700 (PDT) From: Christoph Lameter Subject: Re: [PATCH] Get rid of zone_table In-Reply-To: <450AAA83.3040905@shadowen.org> Message-ID: References: <1158180795.9141.158.camel@localhost.localdomain> <1158184047.9141.164.camel@localhost.localdomain> <450AAA83.3040905@shadowen.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andy Whitcroft Cc: Dave Hansen , linux-mm@kvack.org List-ID: On Fri, 15 Sep 2006, Andy Whitcroft wrote: > The flags field only has a 9 bit space for these value fields. Into > which we normally shove NODE,ZONE. With SPARSEMEM that is SECTION,ZONE > and so there is only room for 6-7 bits of information in this field. > > The section table only contains an adjusted pointer to the mem_map for > that section? We use the bottom two bits of that pointer for a couple > of flags. I don't think there is any space in it. Great! If we only have 6-7 bits that means a max of 128 sections, right? And you have always less than 256 nodes? How about making the section_to_nid array a byte vector? It will then fit into one cacheline and be only little less hot than NODE_DATA() so we should be even faster than before. The zone_table is currently certainly much larger than a single cacheline. -- 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