Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751001AbVJXE7j (ORCPT ); Mon, 24 Oct 2005 00:59:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751002AbVJXE7j (ORCPT ); Mon, 24 Oct 2005 00:59:39 -0400 Received: from gold.veritas.com ([143.127.12.110]:53145 "EHLO gold.veritas.com") by vger.kernel.org with ESMTP id S1750999AbVJXE7i (ORCPT ); Mon, 24 Oct 2005 00:59:38 -0400 Date: Mon, 24 Oct 2005 05:58:45 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Andrew Morton cc: clameter@sgi.com, rmk@arm.linux.org.uk, matthew@wil.cx, jdike@addtoit.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 7/9] mm: split page table lock In-Reply-To: <20051023211630.44459ff7.akpm@osdl.org> Message-ID: References: <20051023142712.6c736dd3.akpm@osdl.org> <20051023152245.4d1dc812.akpm@osdl.org> <20051023211630.44459ff7.akpm@osdl.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 24 Oct 2005 04:59:38.0129 (UTC) FILETIME=[BC354810:01C5D857] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1495 Lines: 34 On Sun, 23 Oct 2005, Andrew Morton wrote: > Hugh Dickins wrote: > > I'm rather surprised that no architectures are already using page.mapping, > .index, .lru or .virtual in pte pages. It is important that we don't corrupt .virtual. But beyond that, why should they use those fields? Some were used in the pte_chains days, and ppc held on to that usage for a while longer (to get from page table to mm), but that is all gone now. Unless I've missed something. > > > ick. I think I prefer the union, although it'll make struct page bigger > > > for CONFIG_PREEMPT+CONFIG_SMP+NR_CPUS>=4. hmm. > > > > Hmm indeed. Definitely not the tradeoff I chose or would choose. > > It's not that bad, really. I do think that this approach is just too > dirty, sorry. We can avoid it by moving something else into the union. > lru, perhaps? Perhaps. But revisiting this is not something I'm prepared to rush into overnight - right answers come slower. I'd rather we start with what I had, tested on few architectures as it is, and consider how to robustify it more sedately. Or, if you prefer, disable the split (raise Kconfig default to "4096"), or back out the 7/9 for the moment; though I had been hoping for exposure. Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/