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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 CB091C74A5B for ; Thu, 11 Jul 2019 16:36:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A02D221721 for ; Thu, 11 Jul 2019 16:36:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728798AbfGKQge convert rfc822-to-8bit (ORCPT ); Thu, 11 Jul 2019 12:36:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38936 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726213AbfGKQgd (ORCPT ); Thu, 11 Jul 2019 12:36:33 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0CA637F7CB; Thu, 11 Jul 2019 16:36:33 +0000 (UTC) Received: from [10.18.17.163] (dhcp-17-163.bos.redhat.com [10.18.17.163]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C984460BFB; Thu, 11 Jul 2019 16:36:02 +0000 (UTC) Subject: Re: [RFC][Patch v11 1/2] mm: page_hinting: core infrastructure To: Dave Hansen , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, pbonzini@redhat.com, lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, yang.zhang.wz@gmail.com, riel@surriel.com, david@redhat.com, mst@redhat.com, dodgen@google.com, konrad.wilk@oracle.com, dhildenb@redhat.com, aarcange@redhat.com, alexander.duyck@gmail.com, john.starks@microsoft.com, mhocko@suse.com References: <20190710195158.19640-1-nitesh@redhat.com> <20190710195158.19640-2-nitesh@redhat.com> <3f9a7e7b-c026-3530-e985-804fc7f1ec31@intel.com> <0b871cf1-e54f-f072-1eaf-511a03c2907f@redhat.com> From: Nitesh Narayan Lal Openpgp: preference=signencrypt Autocrypt: addr=nitesh@redhat.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 11 Jul 2019 16:36:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/11/19 12:22 PM, Dave Hansen wrote: > On 7/11/19 8:25 AM, Nitesh Narayan Lal wrote: >> On 7/10/19 4:45 PM, Dave Hansen wrote: >>> On 7/10/19 12:51 PM, Nitesh Narayan Lal wrote: >>>> +struct zone_free_area { >>>> + unsigned long *bitmap; >>>> + unsigned long base_pfn; >>>> + unsigned long end_pfn; >>>> + atomic_t free_pages; >>>> + unsigned long nbits; >>>> +} free_area[MAX_NR_ZONES]; >>> Why do we need an extra data structure. What's wrong with putting >>> per-zone data in ... 'struct zone'? >> Will it be acceptable to add fields in struct zone, when they will only >> be used by page hinting? > Wait a sec... MAX_NR_ZONES the number of zone types not the maximum > number of *zones* in the system. > > Did you test this on a NUMA system? Yes, I tested it with a guest having 2 and 3 NUMA nodes. > In any case, yes, you can put these in 'struct zone'. It will waste > less space that way, on average, than what you have here (one you scale > it to MAX_NR_ZONE*MAX_NUM_NODES. >>> The cover letter claims that it >>> doesn't touch core-mm infrastructure, but if it depends on mechanisms >>> like this, I think that's a very bad thing. >>> >>> To be honest, I'm not sure this series is worth reviewing at this point. >>> It's horribly lightly commented and full of kernel antipatterns lik >>> >>> void func() >>> { >>> if () { >>> ... indent entire logic >>> ... of function >>> } >>> } >> I usually run checkpatch to detect such indentation issues. For the >> patches, I shared it didn't show me any issues. > Just because checkpatch doesn't complain does not mean it is good form. > We write the above as: > > void func() > { > if (!something) > goto out; > > ... logic of function here > out: > // cleanup > } Yeap, I got it. I will correct this. -- Thanks Nitesh