From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id CB2CA6B0038 for ; Wed, 7 Dec 2016 11:57:03 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id e9so104019171pgc.5 for ; Wed, 07 Dec 2016 08:57:03 -0800 (PST) Received: from mga07.intel.com (mga07.intel.com. [134.134.136.100]) by mx.google.com with ESMTPS id a96si24850703pli.200.2016.12.07.08.57.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Dec 2016 08:57:02 -0800 (PST) From: Dave Hansen Subject: Re: [PATCH kernel v5 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration References: <1480495397-23225-1-git-send-email-liang.z.li@intel.com> <0b18c636-ee67-cbb4-1ba3-81a06150db76@redhat.com> <0b83db29-ebad-2a70-8d61-756d33e33a48@intel.com> <2171e091-46ee-decd-7348-772555d3a5e3@redhat.com> Message-ID: Date: Wed, 7 Dec 2016 08:57:01 -0800 MIME-Version: 1.0 In-Reply-To: <2171e091-46ee-decd-7348-772555d3a5e3@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Hildenbrand , "Li, Liang Z" , "kvm@vger.kernel.org" Cc: "mhocko@suse.com" , "mst@redhat.com" , "qemu-devel@nongnu.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "kirill.shutemov@linux.intel.com" , "pbonzini@redhat.com" , "akpm@linux-foundation.org" , "virtualization@lists.linux-foundation.org" , "dgilbert@redhat.com" , Andrea Arcangeli Removing silly virtio-dev@ list because it's bouncing mail... On 12/07/2016 08:21 AM, David Hildenbrand wrote: >> Li's current patches do that. Well, maybe not pfn/length, but they do >> take a pfn and page-order, which fits perfectly with the kernel's >> concept of high-order pages. > > So we can send length in powers of two. Still, I don't see any benefit > over a simple pfn/len schema. But I'll have a more detailed look at the > implementation first, maybe that will enlighten me :) It is more space-efficient. We're fitting the order into 6 bits, which would allows the full 2^64 address space to be represented in one entry, and leaves room for the bitmap size to be encoded as well, if we decide we need a bitmap in the future. If that was purely a length, we'd be limited to 64*4k pages per entry, which isn't even a full large page. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org