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 E6F01C4332F for ; Fri, 3 Nov 2023 10:50:36 +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 3E6D42A8FE for ; Fri, 3 Nov 2023 10:50:36 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 1F430986C38 for ; Fri, 3 Nov 2023 10:50:36 +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 088B0986C2F; Fri, 3 Nov 2023 10:50:36 +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 02F5D986C30 for ; Fri, 3 Nov 2023 10:50:33 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: rSANdhFQPzyoGhkTKHInHA-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699008629; x=1699613429; 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=kCNBeLO2Yk8tw5MO2i+BDfBOcAqZHmnGcZ1KIdAg0L0=; b=ErUOdAemKaNKbbpIV2JQ7+elDnd+uKqCxKzXO96j6eZqRXldOKSfu5OT+zKLtDH6Hx CP+0sg+ISOQZ9PfehepSTpUnfoagn39cvFatnvK0HtVP8CKVN1jZf2QA97JrhWWuVes+ QkpFNzjQ1IzlDZ7r7s9r5MGkJ1nxyL9wFAE4X3BqAIAVfmf6DyKbvdinAfypc09aGmgB VsG4krpK1WXaelYBXvHzE5pfzrfEQMf8iJ0PqqsJimq1AM5fqD0Y61gzwEn+/MNX6uZZ DNjqesFe74q3TOBE9v7YgZngeI4w0lbWA0BHwwuPYZPcuo30nYVMWCfleUXNs9krTFdc OPJQ== X-Gm-Message-State: AOJu0YzyZvQngp1jT1Ju3sBwtrdQKs0rrABfpHg8Zeqy0evxHpSEvnw+ qZW0kjrx/tvb5JULQLkhcinyzhB3pgqhtXBFjBsVcaYySO75FyxYdI0xb5w5l9TOQb849peCz2K m9UaII7EDeDgHkxgvCad5FTy4F0sLHv2wXg== X-Received: by 2002:a2e:b4bc:0:b0:2c5:fb9:49b6 with SMTP id q28-20020a2eb4bc000000b002c50fb949b6mr14448121ljm.10.1699008629326; Fri, 03 Nov 2023 03:50:29 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHFiOj2cXzTgUZ2W/iVxOogkwEBMKgDVclEEi7fBYt2U7r4RzX/b1Xvb+sgRZc69VaEkFamLA== X-Received: by 2002:a2e:b4bc:0:b0:2c5:fb9:49b6 with SMTP id q28-20020a2eb4bc000000b002c50fb949b6mr14448105ljm.10.1699008628934; Fri, 03 Nov 2023 03:50:28 -0700 (PDT) Date: Fri, 3 Nov 2023 06:50:23 -0400 From: "Michael S. Tsirkin" To: Zhu Lingshan Cc: jasowang@redhat.com, eperezma@redhat.com, cohuck@redhat.com, stefanha@redhat.com, virtio-comment@lists.oasis-open.org, parav@nvidia.com Message-ID: <20231103064730-mutt-send-email-mst@kernel.org> References: <20231103103437.72784-1-lingshan.zhu@intel.com> <20231103103437.72784-7-lingshan.zhu@intel.com> MIME-Version: 1.0 In-Reply-To: <20231103103437.72784-7-lingshan.zhu@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [virtio-comment] Re: [PATCH V2 6/6] virtio-pci: implement dirty page tracking On Fri, Nov 03, 2023 at 06:34:37PM +0800, Zhu Lingshan wrote: > +\item[\field{bitmap_addr}] > + The driver use this to set the address of the bitmap which records the dirty pages > + caused by the device. > + Each bit in the bitmap represents one memory page, bit 0 in the bitmap > + reprsents page 0 at address 0, bit 1 represents page 1, and so on in a linear manner. > + When \field{enable} is set to 1 and the device writes to a memory page, > + the device MUST set the corresponding bit to 1 which indicating the page is dirty. > +\item[\field{bitmap_length}] > + The driver use this to set the length in bytes of the bitmap. > +\end{description} > + > +\devicenormative{\subsubsection}{Memory Dirty Pages Tracker Capability}{Virtio Transport Options / Virtio Over PCI Bus / Memory Dirty Pages Tracker Capability} > + > +The device MUST NOT set any bits beyond bitmap_length when reporting dirty pages. > + > +To prevent a read-modify-write procedure, if a memory page is dirty, > +optionally the device is permitted to set the entire byte, which encompasses the relevant bit, to 1. > + > +The device MAY increase \field{gra_power} to reduce \field{bitmap_length}. > + > +The device must ignore any writes to \field{pasid} if PASID Extended Capability is absent or > +the PASID functionality is disabled in PASID Extended Capability I have to say this is going to work very badly when the number of dirty pages is small: you will end up scanning and re-scanning all of bitmap. And the resolution is apparently 8 pages? You have just multiplied the migration bandwidth by a factor of 8. -- 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/