From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id B23116B0006 for ; Thu, 25 Jan 2018 17:41:28 -0500 (EST) Received: by mail-wr0-f199.google.com with SMTP id 31so5403829wru.0 for ; Thu, 25 Jan 2018 14:41:28 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id d6si4245872wre.377.2018.01.25.14.41.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Jan 2018 14:41:27 -0800 (PST) Date: Thu, 25 Jan 2018 14:41:24 -0800 From: Andrew Morton Subject: Re: [PATCH v25 1/2 RESEND] mm: support reporting free page blocks Message-Id: <20180125144124.7e9f6e2156b1b940b07aecfc@linux-foundation.org> In-Reply-To: <1516873107-34950-1-git-send-email-wei.w.wang@intel.com> References: <1516873107-34950-1-git-send-email-wei.w.wang@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Wei Wang Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com On Thu, 25 Jan 2018 17:38:27 +0800 Wei Wang wrote: > This patch adds support to walk through the free page blocks in the > system and report them via a callback function. Some page blocks may > leave the free list after zone->lock is released, so it is the caller's > responsibility to either detect or prevent the use of such pages. > > One use example of this patch is to accelerate live migration by skipping > the transfer of free pages reported from the guest. A popular method used > by the hypervisor to track which part of memory is written during live > migration is to write-protect all the guest memory. So, those pages that > are reported as free pages but are written after the report function > returns will be captured by the hypervisor, and they will be added to the > next round of memory transfer. It would be useful if we had some quantitative testing results, so we can see the real-world benefits from this change? -- 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