From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 4 Oct 2006 20:26:56 -0700 From: Paul Jackson Subject: Re: [RFC] another way to speed up fake numa node page_alloc Message-Id: <20061004202656.18830f76.pj@sgi.com> In-Reply-To: References: <20060925091452.14277.9236.sendpatchset@v0> <20061001231811.26f91c47.pj@sgi.com> <20061001234858.fe91109e.pj@sgi.com> <20061002014121.28b759da.pj@sgi.com> <20061003111517.a5cc30ea.pj@sgi.com> <20061004084552.a07025d7.pj@sgi.com> <20061004192714.20412e08.pj@sgi.com> <20061004195313.892838e4.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: I don't think you didn't answer my question. I am suggesting we leave it enabled, and I said why. You are suggesting we disable it unless numa nodes are being emulated. Why? What benefit is there to disabling it at runtime? And, no, I can't provide data. It depends on how the system is setup and used. If someone has a system with many nodes (say 64, such as in your fake numa tests) and a cpuset configuration and workload that loads many of those nodes, forcing long zonelist scans, they will hit it just like your tests did. The real question is how common such systems, configurations and workloads really are. No amount of micro-benchmarking can answer that question. Micro-benchmarks are of limited use in making design choices, except when they are validated against real world workloads. And as to why my position changed as to whether the zonelist scans were ever a performance issue on real numa, I've already answered that question ... a couple of times. Let me know if you need me to repeat this answer a third time. -- 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