From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ua0-f176.google.com (mail-ua0-f176.google.com [209.85.217.176]) by dpdk.org (Postfix) with ESMTP id 1E82A68FC for ; Thu, 18 Aug 2016 20:27:07 +0200 (CEST) Received: by mail-ua0-f176.google.com with SMTP id 74so42313201uau.0 for ; Thu, 18 Aug 2016 11:27:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bigswitch-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=IaojLFRU+jACOd2kBSq1lKIOfy8zhsJsXqU4kRkWp2s=; b=W+TdBhtFLOQfQTGAIdfO6H8mU2DL1Jaxgcx9AI+oYhrMzrnv74PeEjqwYC4TfkCzQE LvLPjJ3gECedU7dsRhtUiUs1dh6t61Me+h7e0VPbo1axYxx69qrHTzFSw9eghhksKmrH FfS+AkFrSdZ7YIz7WqC4+3xA7UKpf/m+RMUHG/UFu6+Onhk1LD5twiN4lbKkJPieN1q+ WdR1/WAUqhau0gD4N1f7U9rjK9w47zEjSPpq8Sqm9cmQt+8qjpuvfr5ZOyg2JY0EBTGy xUEaWovzxK0UOb+gCi0kbrisG55C2cDntGdqat84+RyFAs4Zef71mZGSBj2Nh0U8WRTs WBQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=IaojLFRU+jACOd2kBSq1lKIOfy8zhsJsXqU4kRkWp2s=; b=W8/8RzkuQYSwZRtjj8oZnedV6n+jr7NqIl3f+Kd8yHpmXupXCGHQ18mNWo8/BYSVX6 n7ta1E6uH3FBWgRrCDMRSFlsu9k8SiVWsGbcRtnTI4Sz1UllxeLSYiVCm2XGDF5DQSHe 9TlPB+x7quZJX0gJtsFm+DSI49nS1grNVFvKVeMk1Xj2hG1GjmkTVlrwIQsZJaczOKvX rrlZAgXYgRTaBGpj7PgET8k11eJXFhyN0Sn5yuF0MuNVVVcKzy4OUbFMtoQa4R7PXJnW MWsB85357MfIrjjH2qkxaGQkUL4vFlryZI2NY1OmDbzxvzNCbmWNO70WEBBiUjoluSKS 8WDw== X-Gm-Message-State: AEkoouvhZmOwJf/GyvUjIM9n2PFpQ1IL6nWjSZVilolsiZdY/Iy4geujPdGZzQW5bxxSCTwekQYE+3QvA0+WVvE1 X-Received: by 10.176.82.219 with SMTP id w27mr1921535uaw.121.1471544826625; Thu, 18 Aug 2016 11:27:06 -0700 (PDT) MIME-Version: 1.0 Received: by 10.31.50.199 with HTTP; Thu, 18 Aug 2016 11:27:06 -0700 (PDT) In-Reply-To: <20160816023715.GL30752@yliu-dev.sh.intel.com> References: <1471291224-12755-1-git-send-email-rich.lane@bigswitch.com> <20160816023715.GL30752@yliu-dev.sh.intel.com> From: Rich Lane Date: Thu, 18 Aug 2016 11:27:06 -0700 Message-ID: To: Yuanhan Liu Cc: dev@dpdk.org, Huawei Xie Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: Re: [dpdk-dev] [PATCH] vhost: add back support for concurrent enqueue X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Aug 2016 18:27:07 -0000 On Mon, Aug 15, 2016 at 7:37 PM, Yuanhan Liu wrote: > On Mon, Aug 15, 2016 at 01:00:24PM -0700, Rich Lane wrote: > > Concurrent enqueue is an important performance optimization when the > number > > of cores used for switching is different than the number of vhost queues. > > I've observed a 20% performance improvement compared to a strategy that > > binds queues to cores. > > > > The atomic cmpset is only executed when the application calls > > rte_vhost_enqueue_burst_mp. Benchmarks show no performance impact > > when not using concurrent enqueue. > > > > Mergeable RX buffers aren't supported by concurrent enqueue to minimize > > code complexity. > > I think that would break things when Mergeable rx is enabled (which is > actually enabled by default). > Would it be reasonable to return -ENOTSUP in this case, and restrict concurrent enqueue to devices where VIRTIO_NET_F_MRG_RXBUF is disabled? I could also add back concurrent enqueue support for mergeable RX, but I was hoping to avoid that since the mergeable codepath is already complex and wouldn't be used in high performance deployments. > Besides that, as mentioned in the last week f2f talk, do you think adding > a new flag RTE_VHOST_USER_CONCURRENT_ENQUEUE (for > rte_vhost_driver_register()) > __might__ be a better idea? That could save us a API, to which I don't > object > though. > Sure, I can add a flag instead. That will be similar to how the rte_ring library picks the enqueue method.