From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [rfc][patch] mm: scalable vmaps Date: Mon, 18 Feb 2008 11:20:20 +0100 References: <20080218082219.GA2018@wotan.suse.de> <47B94FF7.3030200@goop.org> In-Reply-To: <47B94FF7.3030200@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200802181120.20722.ak@suse.de> Sender: owner-linux-mm@kvack.org Return-Path: To: Jeremy Fitzhardinge Cc: Nick Piggin , David Chinner , Linux Memory Management List List-ID: > Assuming that aliased pages are relatively rare, then its OK for this > function to be heavyweight if it can exit quickly in the non-aliased > case (or there's some other cheap way to tell if a page has aliases). In theory one could use a new struct page flags bit for that purpose. On problem is though that they're already rare on 32bit (although I still think we should just get rid of the flags->zone encoding; then there would be plenty again) And the other problem is that a single bit would directly only work for a single remapping. What would you do if there are multiple remaps of the same page though? I guess for this case you would need to put a reference count into some separate data structure and make vunmap (or however it's called now) search it. Could be ugly. -Andi -- 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