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 4E3A3C352AA for ; Tue, 1 Oct 2019 19:17:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DAFD21855 for ; Tue, 1 Oct 2019 19:17:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726620AbfJATRn (ORCPT ); Tue, 1 Oct 2019 15:17:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42364 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725844AbfJATRn (ORCPT ); Tue, 1 Oct 2019 15:17:43 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D33AE8A1C93; Tue, 1 Oct 2019 19:17:41 +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 93618100EBA2; Tue, 1 Oct 2019 19:17:37 +0000 (UTC) Subject: Re: [PATCH v11 0/6] mm / virtio: Provide support for unused page reporting To: David Hildenbrand , Alexander Duyck , Alexander Duyck , virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org, mst@redhat.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, vbabka@suse.cz, osalvador@suse.de Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, konrad.wilk@oracle.com, riel@surriel.com, lcapitulino@redhat.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com References: <20191001152441.27008.99285.stgit@localhost.localdomain> <7233498c-2f64-d661-4981-707b59c78fd5@redhat.com> <1ea1a4e11617291062db81f65745b9c95fd0bb30.camel@linux.intel.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/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.69]); Tue, 01 Oct 2019 19:17:42 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/1/19 2:41 PM, David Hildenbrand wrote: >>> I think Michal asked for a performance comparison against Nitesh's >>> approach, to evaluate if keeping the reported state + tracking inside >>> the buddy is really worth it. Do you have any such numbers already? (or >>> did my tired eyes miss them in this cover letter? :/) >>> >> I thought what Michal was asking for was what was the benefit of using the >> boundary pointer. I added a bit up above and to the description for patch >> 3 as on a 32G VM it adds up to about a 18% difference without factoring in >> the page faulting and zeroing logic that occurs when we actually do the >> madvise. > "I would still be happier if the allocator wouldn't really have to > bother about somebody snooping its internal state to do its own thing. > So make sure to describe why and how much this really matters. > [...] > if you gave some rough numbers to quantify how much overhead for > different solutions we are talking about here. > " > > Could be that I'm misreading Michals comment, but I'd be interested in > the "how much" as well. > >> Do we have a working patch set for Nitesh's code? The last time I tried >> running his patch set I ran into issues with kernel panics. If we have a >> known working/stable patch set I can give it a try. > @Nitesh, is there a working branch? For some unknown reason, I received these set of emails just now :) That's why couldn't respond earlier. > > -- Thanks Nitesh