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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 38553C352A3 for ; Tue, 11 Feb 2020 16:33:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1AB662086A for ; Tue, 11 Feb 2020 16:33:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730175AbgBKQdU (ORCPT ); Tue, 11 Feb 2020 11:33:20 -0500 Received: from mga09.intel.com ([134.134.136.24]:18514 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728295AbgBKQdT (ORCPT ); Tue, 11 Feb 2020 11:33:19 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Feb 2020 08:33:18 -0800 X-IronPort-AV: E=Sophos;i="5.70,428,1574150400"; d="scan'208";a="237443521" Received: from ahduyck-desk1.jf.intel.com ([10.7.198.76]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Feb 2020 08:33:18 -0800 Message-ID: <3a8d9e1a3a5528c3a0889448f2ffd02c186399b7.camel@linux.intel.com> Subject: Re: [PATCH v16.1 6/9] virtio-balloon: Add support for providing free page reports to host From: Alexander Duyck To: David Hildenbrand , "Michael S. Tsirkin" Cc: Alexander Duyck , kvm@vger.kernel.org, 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, yang.zhang.wz@gmail.com, nitesh@redhat.com, konrad.wilk@oracle.com, pagupta@redhat.com, riel@surriel.com, lcapitulino@redhat.com, dave.hansen@intel.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, osalvador@suse.de Date: Tue, 11 Feb 2020 08:33:18 -0800 In-Reply-To: <314cb54e-8dfc-7606-7135-c21dbf416505@redhat.com> References: <20200122173040.6142.39116.stgit@localhost.localdomain> <20200122174347.6142.92803.stgit@localhost.localdomain> <20200211063441-mutt-send-email-mst@kernel.org> <20200211090052-mutt-send-email-mst@kernel.org> <20200211094357-mutt-send-email-mst@kernel.org> <314cb54e-8dfc-7606-7135-c21dbf416505@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.32.5 (3.32.5-1.fc30) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 2020-02-11 at 16:13 +0100, David Hildenbrand wrote: > >> AFAIKs, the guest could inflate/deflate (esp. temporarily) and > > > communicate via "actual" the actual balloon size as he sees it. > > > > OK so you want hinted but unused pages counted, and reported > > in "actual"? That's a vmexit before each page use ... > > No, not at all. I rather meant, that it is unclear how > inflation/deflation requests and "actual" *could* interact. Especially > if we would consider free page reporting as some way of inflation > (+immediate deflation) triggered by the guest. IMHO, we would not touch > "actual" in that case. > > But as I said, I am totally fine with keeping it as is in this patch. > IOW not glue free page reporting to inflation/deflation but let it act > like something different with its own semantics (and document these > properly). > Okay, so before I post v17 am I leaving the virtio-balloon changes as they were then? For what it is worth I agree with Michael that there is more to this than just a scatter-gather queue. For now I am trying to keep the overall impact on QEMU on the smaller side, and if we do end up supporting the MADV_FREE instead of MADV_DONTNEED that would also have an impact on things as it would be yet another difference between ballooning and hinting. Thanks. - Alex