From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-1266-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Date: Tue, 19 May 2020 08:54:40 +0200 From: Cornelia Huck Message-ID: <20200519085440.1edb9b9c.cohuck@redhat.com> In-Reply-To: References: <158956393696.246123.9443729217250549606.stgit@ahduyck-workstation> <158956398852.246123.13563550180731658368.stgit@ahduyck-workstation> <7558cc20-262b-ddc4-2442-e05f0b74b59d@redhat.com> MIME-Version: 1.0 Subject: Re: [virtio-comment] [PATCH v2 1/3] content: Document balloon feature free page hints Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit To: Alexander Duyck Cc: David Hildenbrand , "Michael S. Tsirkin" , virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org, "Wang, Wei W" List-ID: On Mon, 18 May 2020 13:15:50 -0700 Alexander Duyck wrote: > On Mon, May 18, 2020 at 6:18 AM David Hildenbrand wrote: > > > > On 15.05.20 19:33, Alexander Duyck wrote: > > > +\subsubsection{Free Page Hinting}\label{sec:Device Types / Memory Balloon Device / Device Operation / Free Page Hinting} > > > + > > > +Free page hinting is designed to be used during migration to determine what > > > +pages within the guest are currently unused so that they can be skipped over > > > +while migrating the guest. The device will indicate that it is ready to start > > > +performing hinting by setting the \field{free_page_hint_cmd_id} to one of the > > > +non-reserved values that can be used as a command ID. The following values > > > +are reserved: > > > + > > > +\begin{description} > > > +\item[VIRTIO_BALLOON_CMD_ID_STOP (0)] Any command ID previously supplied by > > > + the device is invalid. The driver should halt all hinting until a new > > > + command ID is supplied. > > > > Maybe "The driver should stop hinting free pages, but should not reuse > > all previously hinted pages." > > The "reuse all previously hinted pages" seems rather unclear to me. I > would like to make clear that in this case the "use" is the guest > making use of the memory, not the driver doing something like > recycling hints. So in the spots where you reference "the driver > reusing pages" I think I might prefer to go with something along the > lines of "releasing pages for use by the guest". The problem is that > when you have a balloon we were referencing using pages from the > balloon. Since we cannot reference the balloon I figure I will go with > language where we "supply" and "release" hinted pages. That way we > acknowledge that the driver is holding onto pages and not freeing them > for use by the guest. > > I'll probably go with something like: > The driver should stop hinting free pages, but > should not release any hinted pages for use by the guest. "The driver should stop hinting free pages until a new command ID is supplied, but should not release..." would sound good to me. > > > > + > > > +\item[VIRTIO_BALLOON_CMD_ID_DONE (1)] Any command ID previously supplied by > > > + the device is invalid. The driver should halt all hinting and the hinting > > > + balloon can now be deflated returning all pages to the guest. > > > > I would avoid the terminology "hinting balloon" and "deflation". > > So I will clean up the spots you pointed out and also work on the > workflow down below that includes "hinting balloon" in the > terminology. > > > "The driver should stop hinting free pages and should reuse all > > previously hinted pages.". > > Similar to the comment above: > The driver should stop hinting free pages, and > should release all hinted pages for use by the guest. Also sounds good to me. This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. Subscribe: virtio-comment-subscribe@lists.oasis-open.org Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org List help: virtio-comment-help@lists.oasis-open.org List archive: https://lists.oasis-open.org/archives/virtio-comment/ Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists Committee: https://www.oasis-open.org/committees/virtio/ Join OASIS: https://www.oasis-open.org/join/