From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 04 Apr 2003 20:52:02 -0800 From: "Martin J. Bligh" Subject: Re: objrmap and vmtruncate Message-ID: <9320000.1049518322@[10.10.2.4]> In-Reply-To: <20030405024414.GP16293@dualathlon.random> References: <20030404163154.77f19d9e.akpm@digeo.com> <12880000.1049508832@flay> <20030405024414.GP16293@dualathlon.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: Andrew Morton , mingo@elte.hu, hugh@veritas.com, dmccr@us.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: >> I'm not convinced that we can't do something with nonlinear mappings for >> this ... we just need to keep a list of linear areas within the nonlinear >> vmas, and use that to do the objrmap stuff with. Dave and I talked about >> this yesterday ... we both had different terminology, but I think the >> same underlying fundamental concept ... I was calling them "sub-vmas" >> for each linear region within the nonlinear space. > > that's wasted memory IMHO, if you need nonlinear, you don't want to > waste further metadata, you only want to pin pages in the pagetables, > the 'window' over the pagecache (incidentally shm) Hold on a minute ... don't the rmap chains (which this would be replacing) waste rather more space than this anyway? I'd rather have it per linear area than per-page ... think of it as "shared rmap pte chains with offsets" if you like ;-) M. -- 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