From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <404D7109.10902@cyberone.com.au> Date: Tue, 09 Mar 2004 18:23:53 +1100 From: Nick Piggin MIME-Version: 1.0 Subject: Re: [RFC][PATCH 4/4] vm-mapped-x-active-lists References: <404D56D8.2000008@cyberone.com.au> <404D5784.9080004@cyberone.com.au> <404D5A6F.4070300@matchmail.com> <404D5EED.80105@cyberone.com.au> <20040309070246.GI655@holomorphy.com> In-Reply-To: <20040309070246.GI655@holomorphy.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: William Lee Irwin III Cc: Mike Fedyk , linux-kernel , Linux Memory Management List-ID: William Lee Irwin III wrote: >On Tue, Mar 09, 2004 at 05:06:37PM +1100, Nick Piggin wrote: > >>Not sure to be honest, I haven't looked at it :\. I'm not really >>sure if the rmap mitigation direction is just a holdover until >>page clustering or intended as a permanent feature... >>Either way, I trust its proponents will take the onus for regressions. >> > >Actually, anobjrmap does wonderful things wrt. liberating pgcl >internals from some very frustrating complications having to do with >assumptions of a 1:1 correspondence between pte pages and struct pages, >so I would regard work in the direction of anobjrmap as useful to >advance the state of page clustering regardless of its rmap mitigation >overtones. The "partial" objrmap is actually insufficient to clean up >this assumption, and introduces new failure modes I don't like (which >it is in fact not necessary to do; aa's code is very close to doing the >partial-but-insufficient-for-pgcl objrmap properly apart from trying to >allocate more pte_chains than necessary and not falling back to the vma >lists for linear/nonlinear mapping mixtures). The current port has some >code to deal with this I'm extremely eager to dump as soon as things >such as anobjrmap etc. make it possible, if they're merged. > >Current efforts are now a background/spare time affair centering around >non-i386 architectures and driver audits. > OK. I had just noticed that the people complaining about rmap most are the ones using 4K page size (x86-64 uses 4K, doesn't it?). Not that this fact means it is OK to ignore them problem, but I thought maybe pgcl might solve it in a more general way. I wonder how much you gain with objrmap / anobjrmap on say a 64K page architecture? -- 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: aart@kvack.org