From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger-Tang Date: Tue, 27 Sep 2005 01:20:08 +0000 Subject: Re: [PATCH 0/4] V4 ia64 SPARSEMEM Message-Id: List-Id: References: <20050922161418.GW16066@localhost.localdomain> In-Reply-To: <20050922161418.GW16066@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On 9/26/05, Luck, Tony wrote: > >Long term should SPARSEMEM become the default and DISCONTIG+VIRTUAL_MEM_MAP > >be obsoleted then we could remove the config files. > > If benchmarks show no difference, then I'll consolidate the > configuration options. I still think that VIRTUAL_MEM_MAP > has a great deal of elegance to it ... auto-sizing to just > about any degree of sparseness, but I think we need to > simplify. Benchmarks cannot prove the absence of a performance difference in *general*, they can only do that for specific tests and workloads. So, unless SPARSEMEM actually performs *better* on some benchmarks (and no worse on others), the proper course seems to be to stick with VIRTUAL_MEM_MAP where SPARSEMEM isn't needed. I have voice my objection in the past to Bob's suggestion that SPARSEMEM should replace VIRTUAL_MEM_MAP and since then I haven't seen any convincing argument why that should be the case, so I do not understand why Bob keeps bringing that up. --david -- Mosberger Consulting LLC, voice/fax: 510-744-9372, http://www.mosberger-consulting.com/ 35706 Runckel Lane, Fremont, CA 94536