From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-x243.google.com (mail-oi1-x243.google.com [IPv6:2607:f8b0:4864:20::243]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 91D1821184E78 for ; Mon, 29 Oct 2018 10:34:35 -0700 (PDT) Received: by mail-oi1-x243.google.com with SMTP id k19-v6so7836451oic.11 for ; Mon, 29 Oct 2018 10:34:35 -0700 (PDT) MIME-Version: 1.0 References: <98c35e19-13b9-0913-87d9-b3f1ab738b61@linux.intel.com> <20181010185242.GP5873@dhcp22.suse.cz> <20181011085509.GS5873@dhcp22.suse.cz> <6f32f23c-c21c-9d42-7dda-a1d18613cd3c@linux.intel.com> <20181017075257.GF18839@dhcp22.suse.cz> <971729e6-bcfe-a386-361b-d662951e69a7@linux.intel.com> <20181029141210.GJ32673@dhcp22.suse.cz> <84f09883c16608ddd2ba88103f43ec6a1c649e97.camel@linux.intel.com> <20181029163528.GL32673@dhcp22.suse.cz> <18dfc5a0db11650ff31433311da32c95e19944d9.camel@linux.intel.com> <20181029172415.GM32673@dhcp22.suse.cz> In-Reply-To: <20181029172415.GM32673@dhcp22.suse.cz> From: Dan Williams Date: Mon, 29 Oct 2018 10:34:22 -0700 Message-ID: Subject: Re: [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Michal Hocko Cc: Pasha Tatashin , linux-nvdimm , Dave Hansen , Linux Kernel Mailing List , Ingo Molnar , Linux MM , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , rppt@linux.vnet.ibm.com, alexander.h.duyck@linux.intel.com, Andrew Morton , "Kirill A. Shutemov" List-ID: On Mon, Oct 29, 2018 at 10:24 AM Michal Hocko wrote: > > On Mon 29-10-18 10:01:28, Alexander Duyck wrote: > > On Mon, 2018-10-29 at 17:35 +0100, Michal Hocko wrote: [..] > > > You are already doing per-page initialization so I fail to see a larger > > > unit to operate on. > > > > I have a patch that makes it so that we can work at a pageblock level > > since all of the variables with the exception of only the LRU and page > > address fields can be precomputed. Doing that is one of the ways I was > > able to reduce page init to 1/3 to 1/4 of the time it was taking > > otherwise in the case of deferred page init. > > You still have to call set_page_links for each page. But let's assume we > can do initialization per larger units. Nothing really prevent to hide > that into constructor as well. A constructor / indirect function call makes sense when there are multiple sub-classes of object initialization, on the table I only see 3 cases: typical hotplug, base ZONE_DEVICE, ZONE_DEVICE + HMM. I think we can look to move the HMM special casing out of line, then we're down to 2. Even at 3 cases we're better off open-coding than a constructor for such a low number of sub-cases to handle. I do not foresee more cases arriving, so I struggle to see what the constructor buys us in terms of code readability / maintainability? _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8517C0044C for ; Mon, 29 Oct 2018 17:34:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A325D2082D for ; Mon, 29 Oct 2018 17:34:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="ERmFGWaT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A325D2082D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727690AbeJ3CYK (ORCPT ); Mon, 29 Oct 2018 22:24:10 -0400 Received: from mail-oi1-f193.google.com ([209.85.167.193]:35428 "EHLO mail-oi1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726532AbeJ3CYJ (ORCPT ); Mon, 29 Oct 2018 22:24:09 -0400 Received: by mail-oi1-f193.google.com with SMTP id v198-v6so5072177oif.2 for ; Mon, 29 Oct 2018 10:34:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=E8MprY7VTm9p0yfpD9lSRFyDxBGNr193lmRNNx0JyUg=; b=ERmFGWaTpLpbrDnTCFAtYXkC/eW6TfOmgw+UVU0niqOQl1nqY7oY4xy8BA2Nm1G1Dr GJI01ajNUXjuX5XI3rgsdn+9f9okIePdkFynNm5u4lXTbPX24q1T15a6p8ipmQVOBUoW 3FO50j4MeIzri8HTFM1SFqtXsPqb+TKBytjoCuooCkyjVZsfJDyjGy/b6STmrVcMUIgr UP49h8F4xq31VPHOMcfKbaGZr3mtaT0Tih4hRKuIq1ke4F5E0nJOLwgRjVIeMMejpNwX l8rIEQHZ2QRX8Mq/oz3qe+r+VKhbbbFTSElOv98B5bzhfk3LEdiB+5IXbjovIIk4tQU1 D2Qg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=E8MprY7VTm9p0yfpD9lSRFyDxBGNr193lmRNNx0JyUg=; b=n6Z7A2XCeRncCTu1v+VZq9HTe/BnmrLG9mLrYI52QPvbgZgxBzIba/Y9HvnZvpEpup DR1vqFWVmtJhM5tpKG4Lixb9ztsLab2TiesnC3a9GWeHoLP024MrB9DY17EHzYVxx8Md cFpnr9p0Eet1/HXDtcFruAO6xalz+49ur/uJ+KUbF+eKZj/+HP/aZRNEVjwjOwxdqxI0 DnJDRjURHTBNO6KE8Xb9q/fcO+7g/M1J1SrkF/36ioWa9Zf7cjYx3x0xbJIxq+4ZWz+d N4lpWkwpGk9R16SrMKsJxI5hWDTNu+kTJBo0MMghIHsDWKREoL1NXeHhEVDWBpNXq6nC 8wgw== X-Gm-Message-State: AGRZ1gLfY0GPPgXkeT+417Bu5FT4nj/pZaPods0N7Jp5v7Glt/Gx4Rhv E+pRDqIvZKoOW/FAtfxnq2+3nC/LiorFDl8uxyf2kw== X-Google-Smtp-Source: AJdET5dYRgdsJxLd35A8W4PXnvrIiU9m4oaIFPeiC1x+cr62TnKUOCtu6wj3ipimPv2lXmmp94F0K5JuFvhaLmHLINc= X-Received: by 2002:aca:590b:: with SMTP id n11-v6mr8492487oib.232.1540834474488; Mon, 29 Oct 2018 10:34:34 -0700 (PDT) MIME-Version: 1.0 References: <98c35e19-13b9-0913-87d9-b3f1ab738b61@linux.intel.com> <20181010185242.GP5873@dhcp22.suse.cz> <20181011085509.GS5873@dhcp22.suse.cz> <6f32f23c-c21c-9d42-7dda-a1d18613cd3c@linux.intel.com> <20181017075257.GF18839@dhcp22.suse.cz> <971729e6-bcfe-a386-361b-d662951e69a7@linux.intel.com> <20181029141210.GJ32673@dhcp22.suse.cz> <84f09883c16608ddd2ba88103f43ec6a1c649e97.camel@linux.intel.com> <20181029163528.GL32673@dhcp22.suse.cz> <18dfc5a0db11650ff31433311da32c95e19944d9.camel@linux.intel.com> <20181029172415.GM32673@dhcp22.suse.cz> In-Reply-To: <20181029172415.GM32673@dhcp22.suse.cz> From: Dan Williams Date: Mon, 29 Oct 2018 10:34:22 -0700 Message-ID: Subject: Re: [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap To: Michal Hocko Cc: alexander.h.duyck@linux.intel.com, Linux MM , Andrew Morton , Linux Kernel Mailing List , linux-nvdimm , Pasha Tatashin , Dave Hansen , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , rppt@linux.vnet.ibm.com, Ingo Molnar , "Kirill A. Shutemov" , Zhang Yi Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 29, 2018 at 10:24 AM Michal Hocko wrote: > > On Mon 29-10-18 10:01:28, Alexander Duyck wrote: > > On Mon, 2018-10-29 at 17:35 +0100, Michal Hocko wrote: [..] > > > You are already doing per-page initialization so I fail to see a larger > > > unit to operate on. > > > > I have a patch that makes it so that we can work at a pageblock level > > since all of the variables with the exception of only the LRU and page > > address fields can be precomputed. Doing that is one of the ways I was > > able to reduce page init to 1/3 to 1/4 of the time it was taking > > otherwise in the case of deferred page init. > > You still have to call set_page_links for each page. But let's assume we > can do initialization per larger units. Nothing really prevent to hide > that into constructor as well. A constructor / indirect function call makes sense when there are multiple sub-classes of object initialization, on the table I only see 3 cases: typical hotplug, base ZONE_DEVICE, ZONE_DEVICE + HMM. I think we can look to move the HMM special casing out of line, then we're down to 2. Even at 3 cases we're better off open-coding than a constructor for such a low number of sub-cases to handle. I do not foresee more cases arriving, so I struggle to see what the constructor buys us in terms of code readability / maintainability?