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 Received: from ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2990DC197A0 for ; Fri, 17 Nov 2023 10:41:04 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id 732DB7410D for ; Fri, 17 Nov 2023 10:41:03 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 4EA82986E27 for ; Fri, 17 Nov 2023 10:41:03 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id 3BC9E986E1C; Fri, 17 Nov 2023 10:41:03 +0000 (UTC) Mailing-List: contact virtio-comment-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 2C2F1986E1D for ; Fri, 17 Nov 2023 10:41:03 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: _SmrKdxBOUOsAvsArnhOUQ-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700217659; x=1700822459; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=9pym5g1SImMLZd474QaZ1zZpE7FpwzkNrSCe9WLRYsA=; b=ALZtFoAtmeh2RAzezDSptTE3FIfcmtVIktZSMM54rzX98uKu69IbxfPmZ+gS7WBV27 Pl8Ve4kA5PA5OIhaEFdhvklxhgaqizc3grTZEpFKwI/ZcO/3OXxIG+Fp+0C2yuRuCbDA G2muCrTKXUcuDxruN72RiyuuWk9jFlBM2y7SU0ajASl2wYimmX3e2+o58NPQrVBPMIK8 5Ajj70dB7qXEX7jopBi2QRQKZV3n8/R54OIeQGfiMEAHCt9Y6NIdHP/SY16vHMdDwlt7 bl0qSnwh30XkyglzLRrZUrZGQ5LxBuFnuggyx2NQH/n6iauLMzY//+HkHCrkGzhN7by9 WyiA== X-Gm-Message-State: AOJu0YwL6WIYc4WO2IS7SolqmS2O9LJDBEh2m1Jk3lr6wNfZuNVK/KhX K6DWmgjy3cs4/gtlPxOlDdmlc5Q+le0Qx9A35IjbU/alEWZA0gWoMNL5dgxZc7foyHDsxhJcL+/ mvzmuHRRxalPX6OWVG2O8e+LFy3pGYu4nTw== X-Received: by 2002:a2e:a593:0:b0:2bc:d8cb:59fe with SMTP id m19-20020a2ea593000000b002bcd8cb59femr9457501ljp.8.1700217659497; Fri, 17 Nov 2023 02:40:59 -0800 (PST) X-Google-Smtp-Source: AGHT+IGd8+1M0JXlmiHFUH2EE566+AVqADswOqD7bATPm3i275u5E77eGaIKG+8QixdThpx2LIhTHA== X-Received: by 2002:a2e:a593:0:b0:2bc:d8cb:59fe with SMTP id m19-20020a2ea593000000b002bcd8cb59femr9457484ljp.8.1700217659154; Fri, 17 Nov 2023 02:40:59 -0800 (PST) Date: Fri, 17 Nov 2023 05:40:54 -0500 From: "Michael S. Tsirkin" To: "Zhu, Lingshan" Cc: Parav Pandit , Jason Wang , "virtio-comment@lists.oasis-open.org" , "cohuck@redhat.com" , "sburla@marvell.com" , Shahaf Shuler , Maor Gottlieb , Yishai Hadas Message-ID: <20231117053844-mutt-send-email-mst@kernel.org> References: <20231116004037-mutt-send-email-mst@kernel.org> <20231116065416-mutt-send-email-mst@kernel.org> <705e728a-368a-4e28-a7b2-61afddb15ce9@intel.com> MIME-Version: 1.0 In-Reply-To: <705e728a-368a-4e28-a7b2-61afddb15ce9@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: Re: [virtio-comment] Re: [PATCH v3 6/8] admin: Add theory of operation for write recording commands On Fri, Nov 17, 2023 at 05:59:35PM +0800, Zhu, Lingshan wrote: > > > On 11/16/2023 7:59 PM, Michael S. Tsirkin wrote: > > On Thu, Nov 16, 2023 at 06:28:07PM +0800, Zhu, Lingshan wrote: > > > > > > On 11/16/2023 1:51 PM, Michael S. Tsirkin wrote: > > > > On Thu, Nov 16, 2023 at 05:29:54AM +0000, Parav Pandit wrote: > > > > > We should expose a limit of the device in the proposed WRITE_RECORD_CAP_QUERY command, that how much range it can track. > > > > > So that future provisioning framework can use it. > > > > > > > > > > I will cover this in v5 early next week. > > > > I do worry about how this can even work though. If you want a generic > > > > device you do not get to dictate how much memory VM has. > > > > > > > > Aren't we talking bit per page? With 1TByte of memory to track -> > > > > 256Gbit -> 32Gbit -> 8Gbyte per VF? > > > > > > > > And you happily say "we'll address this in the future" while at the same > > > > time fighting tooth and nail against adding single bit status registers > > > > because scalability? > > > > > > > > > > > > I have a feeling doing this completely theoretical like this is problematic. > > > > Maybe you have it all laid out neatly in your head but I suspect > > > > not all of TC can picture it clearly enough based just on spec text. > > > > > > > > We do sometimes ask for POC implementation in linux / qemu to > > > > demonstrate how things work before merging code. We skipped this > > > > for admin things so far but I think it's a good idea to start doing > > > > it here. > > > > > > > > What makes me pause a bit before saying please do a PoC is > > > > all the opposition that seems to exist to even using admin > > > > commands in the 1st place. I think once we finally stop > > > > arguing about whether to use admin commands at all then > > > > a PoC will be needed before merging. > > > We have POR productions that implemented the approach in my series. They are > > > multiple generations > > > of productions in market and running in customers data centers for years. > > > > > > Back to 2019 when we start working on vDPA, we have sent some samples of > > > production(e.g., Cascade Glacier) > > > and the datasheet, you can find live migration facilities there, includes > > > suspend, vq state and other > > > features. > > > > > > And there is an reference in DPDK live migration, I have provided this page > > > before: > > > https://doc.dpdk.org/guides-21.11/vdpadevs/ifc.html, it has been working for > > > long long time. > > > > > > So if we let the facts speak, if we want to see if the proposal is proven to > > > work, I would > > > say: They are POR for years, customers already deployed them for years. > > And I guess what you are trying to say is that this patchset > > we are reviewing here should be help to the same standard and > > there should be a PoC? Sounds reasonable. > Yes and the in-marketing productions are POR, the series just improves the > design, > for example, our series also use registers to track vq state, but > improvements > than CG or BSC. So I think they are proven to work. Well yes and no. It works for vdpa because it's a very specific device with very specific behaviour. If it needs to work for virtio generally, then 16 bits of state won't be enough so registers won't work. > > > > > For dirty page tracking, I see you want both platform IOMMU tracking and > > > shadow vqs, I am > > > totally fine with this idea. And I think maybe we should merge the basic > > > features first, and > > > dirty page tracking should be the second step. > > > > > > Thanks > > Parav wants to add an option of on-device tracking. Which also seems > > fine. I think it should be optional though because shadow and IOMMU > > options exist. > I agree, the vendor can choose to implement their own facility as a backup. > > No that is a bad idea if vendor is doing full virtio, things need to be in spec. -- MST 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/