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 A1A37EB64D7 for ; Fri, 16 Jun 2023 14:40:37 +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 CB16918C9C8 for ; Fri, 16 Jun 2023 14:40:36 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 9D5B5986808 for ; Fri, 16 Jun 2023 14:40:36 +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 8A3D4986669; Fri, 16 Jun 2023 14:40:36 +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 76FB8986801 for ; Fri, 16 Jun 2023 14:40:36 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: MYIey-QQMzGZdyl4t1Rldw-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686926433; x=1689518433; h=in-reply-to:content-transfer-encoding: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=VuYMR4FWuF/WtAdytnMzyg+AcAWbjjW4EqaVmg7azwc=; b=KFNoTsKEsdLWMI4NZmNa7DnrkGsSJAix/5wkGjw6I7HQJXeujsC6QKg7DSbOqslAyz NU+/+iiI+/xDXioCdbuZ0AheJHIpB0nD2mw4AQ3BtX206lfmEzZ88tlf3LflTRQhuDr1 8Q7L5d1Wid4BvZoo55LmAvsoWKz98hVMr8iZzX5V5Flz/DfW1nhECqe7N39aTPYz2HJu dZnUir5wT4szjJOssJUlIEGTszsJEE7tWOxHVu6jVqhXd2iFIDftzlpoilgmKWIR4YFT 4v1Af0VT/mMRBOgxtcrv1l3mwoyFgACL3jb1V+junLRVHb7xXt5zT2YPUHAH/SGKO8Qn 2rhg== X-Gm-Message-State: AC+VfDwq1UKLz6EkwLRD5IVib2DqGWZ+RvdyZDpepKa7Biu1NaTjMEAT B09NalI11v2WvhcX6+Kl79MH+mhQKJ6WIr6nX4NUdUM8leJ7eZdbSXpBl1KGHQcvZGvcUTrehif uBbl4k1pIx/TQ/ZDMi2k/bde8ve6mDG7jXQ== X-Received: by 2002:a05:6000:136c:b0:311:500:a5c7 with SMTP id q12-20020a056000136c00b003110500a5c7mr1514794wrz.52.1686926433150; Fri, 16 Jun 2023 07:40:33 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6gG/F2Hq6b7qUtwCCNDOmtV0cVUnwjxwtaQHemzXoJwQwg0Kas5hiyU5ghLZsmIP54o1m7pw== X-Received: by 2002:a05:6000:136c:b0:311:500:a5c7 with SMTP id q12-20020a056000136c00b003110500a5c7mr1514763wrz.52.1686926432772; Fri, 16 Jun 2023 07:40:32 -0700 (PDT) Date: Fri, 16 Jun 2023 10:40:28 -0400 From: "Michael S. Tsirkin" To: Eugenio Perez Martin Cc: Jason Wang , Xuan Zhuo , virtio-comment@lists.oasis-open.org, Laurent Vivier , Cindy Lu , cohuck@redhat.com, alvaro.karsz@solid-run.com, Liuxiangdong , Gautam Dawar , longpeng2@huawei.com, Dragos Tatulea , parav@nvidia.com, stefanha@redhat.com, Harpreet Singh Anand , Stefano Garzarella , Heng Qi , Zhu Lingshan , Shannon Nelson , mgurtovoy@nvidia.com, si-wei.liu@oracle.com Message-ID: <20230616102011-mutt-send-email-mst@kernel.org> References: <20230608180617-mutt-send-email-mst@kernel.org> <20230609115250-mutt-send-email-mst@kernel.org> <20230613034216-mutt-send-email-mst@kernel.org> <20230613035132-mutt-send-email-mst@kernel.org> <20230613082755-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: Re: [virtio-comment] Re: [PATCH 0/2] Selective queue enabling On Thu, Jun 15, 2023 at 10:35:09AM +0200, Eugenio Perez Martin wrote: > On Tue, Jun 13, 2023 at 2:29 PM Michael S. Tsirkin wrote: > > > > On Tue, Jun 13, 2023 at 12:12:43PM +0200, Eugenio Perez Martin wrote: > > > On Tue, Jun 13, 2023 at 9:53 AM Michael S. Tsirkin wrote: > > > > > > > > On Tue, Jun 13, 2023 at 03:46:35AM -0400, Michael S. Tsirkin wrote: > > > > > On Mon, Jun 12, 2023 at 09:56:57AM +0200, Eugenio Perez Martin wrote: > > > > > > > > Another drawback of that is the long time a device can spend to > > > > > > > > reconfigure its memory maps. > > > > > > > > > > > > > > The map is already used for cvq though, I don't see why it would take > > > > > > > much more with this. > > > > > > > > > > > > > > > > > > > In the case of vDPA HW, CVQ maps may not need to reach the device's or > > > > > > platform IOMMU, so the modification of that mapping is way cheaper. > > > > > > > > > > Oh, I get it. It's setup time, but you are right. > > > > > > > > > > > > > taking that into account, does it make > > > > > > > > sense to send a new version with the bit 1 on enable? > > > > > > > > > > > > > > > > Thanks! > > > > > > > > > > > > > > Current hardware won't support the extra bit though. > > > > > > > > > > > > Thinking more about this, I think the following works: > > > > > > > > - enable all queues before DRIVER_OK > > > > - reset all data queues before DRIVER_OK > > > > - DRIVER_OK > > > > - CVQ commands > > > > - re-enable data queues > > > > > > > > > > > > No? > > > > > > > > > > If it is valid to write to queue_reset before DRIVER_OK, then sure. I > > > asked for that in the past at > > > https://lists.oasis-open.org/archives/virtio-dev/202305/msg00329.html > > > . > > > > Well then Jason said: > > we should make svq work without RING_RESET > > but now apparently we went full circle and propose > > a feature bit after all? > > > > My understanding is that RING_RESET covers more than just delaying the > enabling of net data vqs, like to change the address or properties of > vqs after DRIVER_OK. While the late enabling may be easy to implement > in current hw, vq property changes may be more challenging. There are > current HW that only support late enabling but not reconfigure the > queues. Ideally, just the subset of late enabling is needed. > > Does it make sense to change the proposal to something in the line of: > RING_F_LATE_ENABLING: This feature flag is a subset of _F_RING_RESET. > If this feature is negotiated, all vqs start as if the vqs has been > reset before DRIVER_OK. This feature does not allow resetting a queue > once it is live. > > Thanks! Maybe. No idea - I am not a hardware designer. Can some hardware vendors chime in and confirm? It seems like a very very narrow "make my hack work" use-case. And I'm not even sure how well it works. For example what if cvq command enables rss? If the queues in question are not enabled packets will be dropped. So - fix some setups, break others? > > > > > > > > > > > > > > > -- > > > > > 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/ > > > > > > 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/