From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sun, 1 Oct 2006 23:48:58 -0700 From: Paul Jackson Subject: Re: [RFC] another way to speed up fake numa node page_alloc Message-Id: <20061001234858.fe91109e.pj@sgi.com> In-Reply-To: References: <20060925091452.14277.9236.sendpatchset@v0> <20061001231811.26f91c47.pj@sgi.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: David Rientjes Cc: linux-mm@kvack.org, akpm@osdl.org, nickpiggin@yahoo.com.au, ak@suse.de, mbligh@google.com, rohitseth@google.com, menage@google.com, clameter@sgi.com List-ID: David wrote: > It would be nice to be able to scale this so that the speed-up works > efficiently for numa=fake=256 (after NODES_SHIFT is increased from 6 to 8 > on x86_64). I'm not sure what you have in mind by "scale this." We have a linear search of zones ... my speedup just changes the constant multiplier, by converting that search from one that takes one or two cache lines per node, to one that takes an unsigned short, from compact array, per node. This speedup should apply regardless of how many nodes (fake or real or mixed) are present. The fake node case is more interesting, because the usage pattern it anticipates, with many, even most, of a long string of nodes full during ordinary operation, stresses this linear scan more. But whatever benefit this proposal has should be independent of the value of NODES_SHIFT. The systems I care most about, ia64 sn2, are already running with a default NODES_SHIFT of 10. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401 -- 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