Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763079AbXKPTPJ (ORCPT ); Fri, 16 Nov 2007 14:15:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752063AbXKPTO5 (ORCPT ); Fri, 16 Nov 2007 14:14:57 -0500 Received: from gw.goop.org ([64.81.55.164]:43070 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751350AbXKPTO4 (ORCPT ); Fri, 16 Nov 2007 14:14:56 -0500 Message-ID: <473DEC1C.8080506@goop.org> Date: Fri, 16 Nov 2007 11:14:36 -0800 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: Linus Torvalds CC: William Lee Irwin III , Andi Kleen , Ingo Molnar , Thomas Gleixner , Nick Piggin , "H. Peter Anvin" , Linux Kernel Mailing List Subject: Re: Why preallocate pmd in x86 32-bit PAE? References: <473CC0AC.3020500@goop.org> <473DCF73.4070401@goop.org> In-Reply-To: X-Enigmail-Version: 0.95.5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 847 Lines: 19 Linus Torvalds wrote: > So don't do it. Just preallocate for the magic 4-entry PGD. You can make > the special case just be something like > Yes, OK, it makes sense. Conceptually they would be dynamically allocated and freed, but they'd just happen to start allocated, to avoid the tlb flush of populating the pgd of an active pagetable. If you happened to do a 1G munmap, it may end up freeing and reallocating them, but that's going to be very rare. Either way, the other special cases are avoided (though pgd_populate would still need to be correct, on the offchance it gets invoked). J - 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/