From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751865AbdJPKdO (ORCPT ); Mon, 16 Oct 2017 06:33:14 -0400 Received: from mail-wm0-f43.google.com ([74.125.82.43]:48491 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750914AbdJPKdL (ORCPT ); Mon, 16 Oct 2017 06:33:11 -0400 X-Google-Smtp-Source: AOwi7QCa9jcBl7dxrXhSG7mM8E/gvDC2d8YyG0ZI29fi1g5elKNHiv8PkoocKdS7u3NM8G2GRkjL8A== From: Michal Nazarewicz To: Guy Shattah , Michal Hocko , Christopher Lameter Cc: Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Marek Szyprowski , "Aneesh Kumar K . V" , Joonsoo Kim , Anshuman Khandual , Laura Abbott , Vlastimil Babka Subject: Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP_CONTIG) support In-Reply-To: <752b49eb-55c6-5a34-ab41-6e91dd93ea70@mellanox.com> Organization: http://mina86.com/ References: <20171012014611.18725-1-mike.kravetz@oracle.com> <20171012014611.18725-4-mike.kravetz@oracle.com> <20171012143756.p5bv4zx476qkmqhh@dhcp22.suse.cz> <20171013084054.me3kxhgbxzgm2lpr@dhcp22.suse.cz> <20171013152801.nbpk6nluotgbmfrs@dhcp22.suse.cz> <20171013154747.2jv7rtfqyyagiodn@dhcp22.suse.cz> <20171013161736.htumyr4cskfrjq64@dhcp22.suse.cz> <752b49eb-55c6-5a34-ab41-6e91dd93ea70@mellanox.com> Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwBAMAAAClLOS0AAAAJFBMVEWbfGlUPDDHgE57V0jUupKjgIObY0PLrom9mH4dFRK4gmjPs41MxjOgAAACP0lEQVQ4T23Sv2vbQBQHcBk1xE6WyALX107VUEgmn6+ouUwpEQQ6uRjttkWP4CkBg2M0BQLBdPFZYPsyFYo7qEtKDQ7on+t7+nF2Ux8ahD587717OmNYrOvycHsZ+o2r051wHTHysAvGb8ygvgu4QWT0sCmkgZCIEnlV2X8BtyraazFGDuxhmKSQJMlwHQ7v5MHSNxmz78rfElwAa3ieVD9e+hBhjaPDDG6NgFo2f4wBMNIo5YmRtF0RyDgFjJjlMIWbnuM4x9MMfABGTlN4qgIQB4A1DEyA1BHWtfeWNUMwiVJKoqh97KrkOO+qzgluVYLvFCUKAX73nONeBr7BGMdM6Sg0kuep03VywLaIzRiVr+GAzKlpQIsAFnWAG2e6DT5WmWDiudZMIc6hYrMOmeMQK9WX0B+/RfjzL9DI7Y9/Iayn29Ci0r2i4f9gMimMSZLCDMalgQGU5hnUtqAN0OGvEmO1Wnl0C0wWSCEHnuHBqmygxdxA8oWXwbipoc1EoNR9DqOpBpOJrnr0criQab9ZT4LL+wI+K7GBQH30CrhUruilgP9DRTrhVWZCiAyILP+wiuLeCKGTD6r/nc8LOJcAwR6IBTUs+7CASw3QFZ0MdA2PI3zNziH4ZKVhXCRMBjeZ1DWMekKwDCASwExy+NQ86TaykaDAFHO4aP48y4fIcDM5yOG8GcTLbOyp8A8azjJI93JFd1EA6yN8sSxMQJWoABqniRZVykYgRXErzrdqExAoUrRb0xfRp8p2A/4XmfilTtkDZ4cAAAAASUVORK5CYII= X-Face: -TR8(rDTHy/(xl?SfWd1|3:TTgDIatE^t'vop%*gVg[kn$t{EpK(P"VQ=~T2#ysNmJKN$"yTRLB4YQs$4{[.]Fc1)*O]3+XO^oXM>Q#b^ix,O)Zbn)q[y06$`e3?C)`CwR9y5riE=fv^X@x$y?D:XO6L&x4f-}}I4=VRNwiA^t1-ZrVK^07.Pi/57c_du'& OpenPGP: id=AC1F5F5CD41888F8CC8458582060401250751FF4; url=http://mina86.com/mina86.pub X-Hashcash: 1:20:171016:khandual@linux.vnet.ibm.com::AISN5J4/0UCOpjQm:00000000000000000000000000000000000EbU X-Hashcash: 1:20:171016:linux-api@vger.kernel.org::iws0C4RPxoJc1Pls:000000000000000000000000000000000000040D X-Hashcash: 1:20:171016:mhocko@kernel.org::nzPIlorKPVBHEqbh:000000000000000000000000000000000000000000000lRW X-Hashcash: 1:20:171016:vbabka@suse.cz::REK8JTLKONIZueul:0001ZkP X-Hashcash: 1:20:171016:labbott@redhat.com::vT0Putlq6dqywPx0:00000000000000000000000000000000000000000003MfE X-Hashcash: 1:20:171016:aneesh.kumar@linux.vnet.ibm.com::rui05SXDlJUwfQtc:0000000000000000000000000000002MRM X-Hashcash: 1:20:171016:linux-kernel@vger.kernel.org::xXOsE01QDaav6vrU:0000000000000000000000000000000001wey X-Hashcash: 1:20:171016:linux-mm@kvack.org::tGKFDtGgBu2YE+3r:00000000000000000000000000000000000000000006c5e X-Hashcash: 1:20:171016:mike.kravetz@oracle.com::tacfCurzQoTBVYP5:000000000000000000000000000000000000002T/C X-Hashcash: 1:20:171016:cl@linux.com::vOC69gSfSXvsOtlW:000002NST X-Hashcash: 1:20:171016:sguy@mellanox.com::62neKlXzIL1UVB2o:000000000000000000000000000000000000000000005sw1 X-Hashcash: 1:20:171016:iamjoonsoo.kim@lge.com::ZL/5GnneEYhkqf0y:0000000000000000000000000000000000000006GaY X-Hashcash: 1:20:171016:m.szyprowski@samsung.com::TzqybxhRw4zEW/dr:0000000000000000000000000000000000000Ddpo Date: Mon, 16 Oct 2017 12:33:07 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v9GAXLOj004597 On Sun, Oct 15 2017, Guy Shattah wrote: > Why have several driver specific implementation if you can generalize > the idea and implement an already existing POSIX standard? Why is there a need for contiguous allocation? CPU cares only to the point of huge pages and there’s already an effort in the kernel to allocate huge pages transparently without user space being aware of it. If not CPU than various devices all of which may have very different needs. Some may be behind an IO MMU. Some may support DMA. Some may indeed require physically continuous memory. How is user space to know? Furthermore, user space does not care whether allocation is physically contiguous or not. What it cares about is whether given allocation can be passed as a buffer to a particular device. If generalisation is the issue, then the solution is to define a common API where user-space can allocate memory *in the context of* a device. This provides a ‘give me memory I can use for this device’ request which is what user space really wants. So yeah, like others in this thread, the reason for this change alludes me. On the other hand, I don’t care much so I’ll limit myself to this one message. -- Best regards ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ «If at first you don’t succeed, give up skydiving»