From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out3-smtp.messagingengine.com (out3-smtp.messagingengine.com [66.111.4.27]) by dpdk.org (Postfix) with ESMTP id AF8065599 for ; Mon, 10 Jul 2017 00:49:47 +0200 (CEST) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id 467A22085C; Sun, 9 Jul 2017 18:49:47 -0400 (EDT) Received: from frontend1 ([10.202.2.160]) by compute1.internal (MEProxy); Sun, 09 Jul 2017 18:49:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=monjalon.net; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-sender :x-me-sender:x-sasl-enc:x-sasl-enc; s=mesmtp; bh=VIlA5Po/NYCqEax e2u9XWzqdlKEX7vHWtZO6pwsvB/E=; b=Mu9PCGn0LL4psQd0S1kAkxJ+UugZ6XX HNxRXv02hRWT0zSYCm6C/KbjyKpnL2TemZKDjD7Ts7OXxPgm/4zRbLRGhk5PoE2I M1qrKpEYVQtAcx6bCkfxmv8DEGt1qj1+HtzG2LAkk2bPqS93q63QfCBZ2TNLQlID VKn3z/5o+s+o= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-me-sender:x-me-sender:x-sasl-enc:x-sasl-enc; s= fm1; bh=VIlA5Po/NYCqEaxe2u9XWzqdlKEX7vHWtZO6pwsvB/E=; b=XkK0TOks D3BAUpkF1YshXP6hKEIOah3th3xhKp3MB8+GuxpgYEQmhqs/795pc73Rd69iDYsr fSCg8nDMBfrQ1n7Wn0pDWAlm1QMLY/1vA6HdfJGrGa5r8oQHTRx0qpLfSmS1DGJI 0kCJXKYj1wqmrTRjDwbagsiYTHTXK8iuLTmWRG31jilPPbREPgsrjG4vNJl0tKmY RLjnbju9mkIalmu10JE93zNf3nrQa0Ff0kGr/3PuXM8UlPVd5zDWXIFWpP3hpkOe PXB4gmR8i0N4G91ey92sKhY6mMpHuQY1q2xjB81m0pMd3sQLzCBcEtqeLFK3A0hk gSu17UTbK2/ZlQ== X-ME-Sender: X-Sasl-enc: 5UBv0HT71fOX1SiMk0dqd8iDrZ/bdF1FVWbl5PykWixw 1499640586 Received: from xps.localnet (184.203.134.77.rev.sfr.net [77.134.203.184]) by mail.messagingengine.com (Postfix) with ESMTPA id EE24A7E6EE; Sun, 9 Jul 2017 18:49:46 -0400 (EDT) From: Thomas Monjalon To: Qi Zhang Cc: dev@dpdk.org, john.mcnamara@intel.com, jingjing.wu@intel.com, helin.zhang@intel.com Date: Mon, 10 Jul 2017 00:49:46 +0200 Message-ID: <5809031.eT3YHgoUoZ@xps> In-Reply-To: <20170703035754.4622-1-qi.z.zhang@intel.com> References: <20170703035754.4622-1-qi.z.zhang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [dpdk-dev] [PATCH v2] doc: add known issue for i40e VF performance X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Jul 2017 22:49:48 -0000 Hi, Few typos spotted 03/07/2017 05:57, Qi Zhang: > --- a/doc/guides/nics/i40e.rst > +++ b/doc/guides/nics/i40e.rst > @@ -447,3 +447,30 @@ It means if APP has set the max bandwidth for that TC, it comes to no > effect. > It's suggested to set the strict priority mode for a TC that is latency > sensitive but no consuming much bandwidth. > + > +VF performance is impacted by PCI extended tag setting > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + > +To reach maximum NIC performance in the VF the PCI extended tag must be > +enabled. The DPDK I40E PF drvier will set this feature during initialization, drvier -> driver > +but the kernel PF driver does not. So when running traffic on a VF which is > +managed by the kernel PF driver, a significent NIC performance downgrade has significent -> significant > +been observed (for 64 byte packets, there is about 25% linerate downgrade for > +a 25G device and about 35% for a 40G device). > + > +For kernel version >= 4.11, the kernel's PCI driver will enable the extended > +tag if it detects that the device supports it. So by default, this is not an > +issue. For kernels <= 4.11 or When the PCI extended tag is disabled it can be When -> when > +enabled using the steps below. > + > +#. Get the current value of the PCI configure register:: > + > + setpci -s a8.w > + > +#. Set bit 8:: > + > + value = value | 0x100 > + > +#. Set the PCI configure register with new value:: > + > + setpci -s a8.w=