From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S977614AbdDXUdz (ORCPT ); Mon, 24 Apr 2017 16:33:55 -0400 Received: from outpost1.zedat.fu-berlin.de ([130.133.4.66]:47687 "EHLO outpost1.zedat.fu-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S976692AbdDXUdp (ORCPT ); Mon, 24 Apr 2017 16:33:45 -0400 Subject: Re: Question on the five-level page table support patches To: Andi Kleen , Andy Lutomirski References: <030ea57b-5f6c-13d8-02f7-b245a754a87d@physik.fu-berlin.de> <20170424130311.GR4021@tassilo.jf.intel.com> Cc: "Kirill A. Shutemov" , "linux-kernel@vger.kernel.org" , Dave Hansen , Michal Hocko , linux-arch , "linux-mm@kvack.org" From: John Paul Adrian Glaubitz Message-ID: <8f8467b5-70e6-466b-f53b-1c64622ba82d@physik.fu-berlin.de> Date: Mon, 24 Apr 2017 22:33:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170424130311.GR4021@tassilo.jf.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Originating-IP: 87.193.181.242 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/24/2017 03:03 PM, Andi Kleen wrote: > In old Linux hint was a search hint, so if there isn't a hole > at the hinted area it will search starting from there for a hole > instead of giving up immediately. Yep, that's what I meant. It used to work like that and it still works like that on NetBSD, for example. Although it has apparently been a long time since it changed [1]. > Now it just gives up, which means every user has to implement > their own search. Correct. And the resulting code is usually ugly and inefficient [2]. > Yes I ran into the same problem and it's annoying. It broke > originally when top down mmap was added I believe > > Before the augmented rbtree it was potentially very expensive, but now > it should be cheap. I'm not sure whether I understand what that means. Thanks, Adrian > [1] http://lkml.iu.edu/hypermail/linux/kernel/0305.2/0828.html > [2] https://hg.mozilla.org/mozilla-central/rev/dfaafbaaa291 -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer - glaubitz@debian.org `. `' Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913