From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id A55A86B003D for ; Thu, 5 Feb 2009 18:42:49 -0500 (EST) Date: Fri, 6 Feb 2009 00:42:41 +0100 From: Ingo Molnar Subject: Re: pud_bad vs pud_bad Message-ID: <20090205234241.GA14203@elte.hu> References: <498B2EBC.60700@goop.org> <20090205184355.GF5661@elte.hu> <498B35F9.601@goop.org> <20090205191017.GF20470@elte.hu> <498B4F1F.5070306@goop.org> <498B54A0.7040005@goop.org> <20090205215050.GB28097@elte.hu> <498B6325.1040401@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <498B6325.1040401@goop.org> Sender: owner-linux-mm@kvack.org To: Jeremy Fitzhardinge Cc: Hugh Dickins , William Lee Irwin III , Linux Kernel Mailing List , Linux Memory Management List List-ID: * Jeremy Fitzhardinge wrote: > Ingo Molnar wrote: >> We'd also lose a fair bit of performance (not to mention the pagetable >> footprint doubling that Hugh already mentioned) on 32-bit PAE capable >> systems that dont actually have RAM above 4G physical. > > Why's that? Do you mean directly from using PAE, or as a side-effect of > highmem? just the act of using PAE was measured to cause multi-percent slowdown in fork() and exec() latencies, etc. The pagetables are twice as large so is that really surprising? Ingo -- 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