From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by uproxy.gmail.com with SMTP id m3so35030uge for ; Wed, 08 Feb 2006 19:38:43 -0800 (PST) Message-ID: Date: Thu, 9 Feb 2006 12:38:43 +0900 From: Magnus Damm Subject: Re: [RFC] Removing page->flags In-Reply-To: <43EAB395.6000603@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Content-Disposition: inline References: <1139381183.22509.186.camel@localhost> <43EAA0F4.2060208@jp.fujitsu.com> <43EAB395.6000603@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Magnus Damm , linux-mm@kvack.org, Magnus Damm List-ID: On 2/9/06, KAMEZAWA Hiroyuki wrote: > Magnus Damm wrote: > > Hi Kamezawa-san, > > > > On 2/9/06, KAMEZAWA Hiroyuki wrote: > >> Magnus Damm wrote: > >>> [RFC] Removing page-flags > >>> > >>> Moving type A bits: > >>> > >>> Instead of keeping the bits together, we spread them out and store a > >>> pointer to them from pg_data_t. > >>> > >> This will annoy people who has a job to look into crash-dump's vmcore..like me ;) > >> so, I don't like this idea. > > > > Hehe, gotcha. =) I also wonder how well it would work with your zone patches. > > > My layout-free-zone patches are not affected by this if you use pgdat/section to > preserve page-flags. Ok, good. > To be honest, I'd like to do this > == > struct zone *page_zone(struct page *page) > { > return page->zone; > } > == > But this increases size of memmap awfully ;( and I can't. > Current zone-indexing in page-flags is well saving memory space, I think. With my proposal (Removing type B bits), if you can guarantee that all your zones have a start address and a size that is aligned to (1 << (PAGE_SHIFT * 2)), then the following code should be possible: struct zone *page_zone(struct page *page) { struct page *parent = virt_to_page(page); return (struct zone *)parent->mapping; } This assumes that the first entry in mem_map is aligned to PAGE_SIZE, and that some code has setup parent->mapping to point to the correct zone. =) / magnus -- 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