From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 18 Dec 2004 10:50:50 +0100 From: Andi Kleen Subject: Re: [PATCH 4/10] alternate 4-level page tables patches Message-ID: <20041218095050.GC338@wotan.suse.de> References: <41C3D453.4040208@yahoo.com.au> <41C3D479.40708@yahoo.com.au> <41C3D48F.8080006@yahoo.com.au> <41C3D4AE.7010502@yahoo.com.au> <41C3D4C8.1000508@yahoo.com.au> <41C3F2D6.6060107@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <41C3F2D6.6060107@yahoo.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Linux Memory Management , Andi Kleen , Hugh Dickins , Linus Torvalds , Andrew Morton List-ID: On Sat, Dec 18, 2004 at 08:05:26PM +1100, Nick Piggin wrote: > Nick Piggin wrote: > >4/10 > > > > > >------------------------------------------------------------------------ > > > > > > > >Rename clear_page_tables to clear_page_range. clear_page_range takes byte > >ranges, and aggressively frees page table pages. Maybe useful to control > >page table memory consumption on 4-level architectures (and even 3 level > >ones). > > > > I maybe didn't do this patch justice by hiding it away in this series. > It may be worthy of its own thread - surely there must be some significant > downsides if nobody had implemented it in the past (or maybe just a fact > of "that doesn't happen much"). Yes, more could be done in this area. When I did 4level I just tried to keep the same semantics without optimizing anything. Another way I thought about was to have a reference count of the used ptes/pmds per page table page in struct page and free the page when it goes to zero. That would give perfect garbage collection. Drawback is that it may be a bit intrusive again. -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: aart@kvack.org