From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750961AbVHYOr2 (ORCPT ); Thu, 25 Aug 2005 10:47:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750966AbVHYOr1 (ORCPT ); Thu, 25 Aug 2005 10:47:27 -0400 Received: from rwcrmhc14.comcast.net ([216.148.227.89]:42647 "EHLO rwcrmhc12.comcast.net") by vger.kernel.org with ESMTP id S1750949AbVHYOr1 (ORCPT ); Thu, 25 Aug 2005 10:47:27 -0400 Subject: Re: process creation time increases linearly with shmem From: Parag Warudkar To: Andi Kleen Cc: Ray Fucillo , linux-kernel@vger.kernel.org In-Reply-To: <200508251622.08456.ak@suse.de> References: <082520051405.5272.430DD0420003F49F00001498220076139400009A9B9CD3040A029D0A05@comcast.net> <200508251622.08456.ak@suse.de> Content-Type: text/plain Date: Thu, 25 Aug 2005 10:47:20 -0400 Message-Id: <1124981240.3055.5.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2005-08-25 at 16:22 +0200, Andi Kleen wrote: > But I'm not sure it's a good idea in all cases. Would need a lot of > benchmarking at least. > > -Andi > Exactly - one problem is that this forces all of the hugetlb users to go the lazy faulting way. This is more or less similar to the original problem the fork() forces everything to be mapped and some apps don't like it. Same way, some apps may not want hugetlb pages to be all pre-mapped. That's why I was alluding towards having the user specify MAP_SHARED| MAP_LAZY or something to that tune and then have fork() honor it. So people who want all things pre-mapped will not specify MAP_LAZY, just MAP_SHARED. Now I don't even know if above is possible and workable for all scenarios but that's why I was asking.. :) Parag