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 AACDFEB64DC for ; Thu, 29 Jun 2023 11:55:41 +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 0E9108508B for ; Thu, 29 Jun 2023 11:55:41 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id EF97B986639 for ; Thu, 29 Jun 2023 11:55:40 +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 E32AF9865CA; Thu, 29 Jun 2023 11:55:40 +0000 (UTC) Mailing-List: contact virtio-dev-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 D1F859865A8 for ; Thu, 29 Jun 2023 11:55:40 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: NJtZeaC5PmKIlHJq5YZWVg-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688039737; x=1690631737; 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=jON5Zm4Gwvo1ka51uxCxMPmcEgxBmFQ/OarQ7lKwJhU=; b=aOr+01eXwZyHgc8wudtUJLVk7h66EZD9+xXmEgMC24LLmyrnJWIkphFX+aGqdcaL9r fcwj4jC2BM08qJ1RJaIwQpYhsNM6cWbp6XX9ZpnKcuYelcVBh71eNWKajsC8Vvr7yhN4 zZiK13RQqSlLxCZyXy0vaUg6uWnlJDRTPSZFyDgOECZL9SS9MkFl1skWT4+/INl4rauy OUyGJbyqA8dC575VNHB+KrsBIvScgGWLiU0ClRVRz1cXGM41qFI425JfpMJyOhT09E35 sszioAn8BJbDZt42rqX7wQBO9cAHkIykDXeUkSpboHdUXNM500KTtn9Vm9daUMxlDAzV 1QrA== X-Gm-Message-State: AC+VfDyxtDpJlBHEBCumfvRPukEcUyFDGsg9XB5XO/DK3RWi9PJS4thh 1q4T+QuDq2KCINXtvon2MJeqJ80wU+IkkXIQwwYmI8qVHRPGR7IoEbSxYIDPRKLrSugFTtqkgTV A7diBSiMWYNSAv7jAadPg2+hhzoV7 X-Received: by 2002:a05:6512:ad4:b0:4fb:76f7:fde9 with SMTP id n20-20020a0565120ad400b004fb76f7fde9mr9199045lfu.30.1688039737153; Thu, 29 Jun 2023 04:55:37 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5q/DOyWFCz8gkQgDVltGEwXr1cOVl4H+zJQhtRIJdnrDN1FlIR4BP0ibwsh+GGUALHBvcPNQ== X-Received: by 2002:a05:6512:ad4:b0:4fb:76f7:fde9 with SMTP id n20-20020a0565120ad400b004fb76f7fde9mr9199038lfu.30.1688039736690; Thu, 29 Jun 2023 04:55:36 -0700 (PDT) Date: Thu, 29 Jun 2023 07:55:32 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: Heng Qi , virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org, Parav Pandit , Yuri Benditovich , Xuan Zhuo Message-ID: <20230629075441-mutt-send-email-mst@kernel.org> References: <20230627163549.40028-1-hengqi@linux.alibaba.com> <20230628060519-mutt-send-email-mst@kernel.org> <2522ab61-a333-a33b-784c-01ea6b4b42da@redhat.com> <20230629074925-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: <20230629074925-mutt-send-email-mst@kernel.org> 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: [virtio-dev] Re: [virtio-comment] Re: [PATCH v19] virtio-net: support inner header hash On Thu, Jun 29, 2023 at 07:54:29AM -0400, Michael S. Tsirkin wrote: > On Thu, Jun 29, 2023 at 11:31:58AM +0800, Jason Wang wrote: > > > > 在 2023/6/28 18:10, Michael S. Tsirkin 写道: > > > On Wed, Jun 28, 2023 at 11:46:22AM +0800, Jason Wang wrote: > > > > On Wed, Jun 28, 2023 at 12:35 AM Heng Qi wrote: > > > > > 1. Currently, a received encapsulated packet has an outer and an inner header, but > > > > > the virtio device is unable to calculate the hash for the inner header. The same > > > > > flow can traverse through different tunnels, resulting in the encapsulated > > > > > packets being spread across multiple receive queues (refer to the figure below). > > > > > However, in certain scenarios, we may need to direct these encapsulated packets of > > > > > the same flow to a single receive queue. This facilitates the processing > > > > > of the flow by the same CPU to improve performance (warm caches, less locking, etc.). > > > > > > > > > > client1 client2 > > > > > | +-------+ | > > > > > +------->|tunnels|<--------+ > > > > > +-------+ > > > > > | | > > > > > v v > > > > > +-----------------+ > > > > > | monitoring host | > > > > > +-----------------+ > > > > > > > > > > To achieve this, the device can calculate a symmetric hash based on the inner headers > > > > > of the same flow. > > > > > > > > > > 2. For legacy systems, they may lack entropy fields which modern protocols have in > > > > > the outer header, resulting in multiple flows with the same outer header but > > > > > different inner headers being directed to the same receive queue. This results in > > > > > poor receive performance. > > > > > > > > > > To address this limitation, inner header hash can be used to enable the device to advertise > > > > > the capability to calculate the hash for the inner packet, regaining better receive performance. > > > > > > > > > > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/173 > > > > > Signed-off-by: Heng Qi > > > > > Reviewed-by: Xuan Zhuo > > > > > Reviewed-by: Parav Pandit > > > > > --- > > > > > v18->v19: > > > > > 1. Have a single structure instead of two. @Michael S . Tsirkin > > > > > 2. Some small rewrites. @Michael S . Tsirkin > > > > > 3. Rebase to master. > > > > > > > > > > v17->v18: > > > > > 1. Some rewording suggestions from Michael (Thanks!). > > > > > 2. Use 0 to disable inner header hash and remove > > > > > VIRTIO_NET_HASH_TUNNEL_TYPE_NONE. > > > > > v16->v17: > > > > > 1. Some small rewrites. @Parav Pandit > > > > > 2. Add Parav's Reviewed-by tag (Thanks!). > > > > > > > > > > v15->v16: > > > > > 1. Remove the hash_option. In order to delimit the inner header hash and RSS > > > > > configuration, the ability to configure the outer src udp port hash is given > > > > > to RSS. This is orthogonal to inner header hash, which will be done in the > > > > > RSS capability extension topic (considered as an RSS extension together > > > > > with the symmetric toeplitz hash algorithm, etc.). @Parav Pandit @Michael S . Tsirkin > > > > > 2. Fix a 'field' typo. @Parav Pandit > > > > > > > > > > v14->v15: > > > > > 1. Add tunnel hash option suggested by @Michael S . Tsirkin > > > > > 2. Adjust some descriptions. > > > > > > > > > > v13->v14: > > > > > 1. Move supported_hash_tunnel_types from config space into cvq command. @Parav Pandit > > > > I may miss some discussions, but this complicates the provisioning a lot. > > > > > > > > Having it in the config space, then a type agnostic provisioning > > > > through config space + feature bits just works fine. > > > > > > > > If we move it only via cvq, we need device specific provisioning interface. > > > > > > > > Thanks > > > Yea that's what I said too. Debugging too. I think we should build a > > > consistent solution that allows accessing config space through DMA, > > > separately from this effort. Parav do you think you can live with this > > > approach so this specific proposal can move forward? > > > > > > We can probably go another way, invent a new device configuration space > > capability which fixed size like PCI configuration access capability? > > > > struct virtio_pci_cfg_cap { > >         struct virtio_pci_cap cap; > >         u8 dev_cfg_data[4]; /* Data for device configuration space access. > > */ > > }; > > > > So it won't grow as the size of device configuration space grows. > > > > Thanks > > It is true, it does not have to be DMA strictly speaking. > > The basic issue is with synchronous access. > > We can change the capability in some way to allow asynch then > that works. E.g. make device change length to 0 and driver > must poll before considering the operation done. > > Having said that, this will increase # of VM exits even more. > Not a fan, DMA seems cleaner. And again, I am now guilty of this too - hijacking inner hash thread for config space change discussions :( Let's all stop please, start a new thread wen we are ready. -- MST --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org