From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2997312AbdD2KRi (ORCPT ); Sat, 29 Apr 2017 06:17:38 -0400 Received: from mail-wm0-f46.google.com ([74.125.82.46]:37351 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1035182AbdD2KRa (ORCPT ); Sat, 29 Apr 2017 06:17:30 -0400 Date: Sat, 29 Apr 2017 13:17:26 +0300 From: "Kirill A. Shutemov" To: Jerome Glisse Cc: Dan Williams , Ingo Molnar , "linux-kernel@vger.kernel.org" , Linux MM , Ingo Molnar , Andrew Morton , Logan Gunthorpe , Kirill Shutemov Subject: Re: [PATCH v2] mm, zone_device: replace {get, put}_zone_device_page() with a single reference Message-ID: <20170429101726.cdczojcjjupb7myy@node.shutemov.name> References: <20170428063913.iz6xjcxblecofjlq@gmail.com> <149339998297.24933.1129582806028305912.stgit@dwillia2-desk3.amr.corp.intel.com> <1743017574.4309811.1493400875692.JavaMail.zimbra@redhat.com> <1579714997.4315035.1493402406629.JavaMail.zimbra@redhat.com> <1295710462.4327805.1493406971970.JavaMail.zimbra@redhat.com> <20170428193305.GA3912@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170428193305.GA3912@redhat.com> User-Agent: NeoMutt/20170306 (1.8.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 28, 2017 at 03:33:07PM -0400, Jerome Glisse wrote: > On Fri, Apr 28, 2017 at 12:22:24PM -0700, Dan Williams wrote: > > Are you sure about needing to hook the 2 -> 1 transition? Could we > > change ZONE_DEVICE pages to not have an elevated reference count when > > they are created so you can keep the HMM references out of the mm hot > > path? > > 100% sure on that :) I need to callback into driver for 2->1 transition > no way around that. If we change ZONE_DEVICE to not have an elevated > reference count that you need to make a lot more change to mm so that > ZONE_DEVICE is never use as fallback for memory allocation. Also need > to make change to be sure that ZONE_DEVICE page never endup in one of > the path that try to put them back on lru. There is a lot of place that > would need to be updated and it would be highly intrusive and add a > lot of special cases to other hot code path. Could you explain more on where the requirement comes from or point me to where I can read about this. -- Kirill A. Shutemov From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id B56E86B02E1 for ; Sat, 29 Apr 2017 06:17:30 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id u5so4522466wmg.13 for ; Sat, 29 Apr 2017 03:17:30 -0700 (PDT) Received: from mail-wm0-x22f.google.com (mail-wm0-x22f.google.com. [2a00:1450:400c:c09::22f]) by mx.google.com with ESMTPS id f17si10323446wra.256.2017.04.29.03.17.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 29 Apr 2017 03:17:29 -0700 (PDT) Received: by mail-wm0-x22f.google.com with SMTP id r190so65689234wme.1 for ; Sat, 29 Apr 2017 03:17:28 -0700 (PDT) Date: Sat, 29 Apr 2017 13:17:26 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCH v2] mm, zone_device: replace {get, put}_zone_device_page() with a single reference Message-ID: <20170429101726.cdczojcjjupb7myy@node.shutemov.name> References: <20170428063913.iz6xjcxblecofjlq@gmail.com> <149339998297.24933.1129582806028305912.stgit@dwillia2-desk3.amr.corp.intel.com> <1743017574.4309811.1493400875692.JavaMail.zimbra@redhat.com> <1579714997.4315035.1493402406629.JavaMail.zimbra@redhat.com> <1295710462.4327805.1493406971970.JavaMail.zimbra@redhat.com> <20170428193305.GA3912@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170428193305.GA3912@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jerome Glisse Cc: Dan Williams , Ingo Molnar , "linux-kernel@vger.kernel.org" , Linux MM , Ingo Molnar , Andrew Morton , Logan Gunthorpe , Kirill Shutemov On Fri, Apr 28, 2017 at 03:33:07PM -0400, Jerome Glisse wrote: > On Fri, Apr 28, 2017 at 12:22:24PM -0700, Dan Williams wrote: > > Are you sure about needing to hook the 2 -> 1 transition? Could we > > change ZONE_DEVICE pages to not have an elevated reference count when > > they are created so you can keep the HMM references out of the mm hot > > path? > > 100% sure on that :) I need to callback into driver for 2->1 transition > no way around that. If we change ZONE_DEVICE to not have an elevated > reference count that you need to make a lot more change to mm so that > ZONE_DEVICE is never use as fallback for memory allocation. Also need > to make change to be sure that ZONE_DEVICE page never endup in one of > the path that try to put them back on lru. There is a lot of place that > would need to be updated and it would be highly intrusive and add a > lot of special cases to other hot code path. Could you explain more on where the requirement comes from or point me to where I can read about this. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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