From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f176.google.com (mail-ig0-f176.google.com [209.85.213.176]) by dpdk.org (Postfix) with ESMTP id E5DD7595A for ; Mon, 21 Jul 2014 02:18:19 +0200 (CEST) Received: by mail-ig0-f176.google.com with SMTP id hn18so2313166igb.9 for ; Sun, 20 Jul 2014 17:19:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc:content-type; bh=lmT08xmkCGBcc1JMLCj+v9q7ZlzOw5EA0UZ0uEycOEI=; b=UTTBRfoJoF8oqxU0M/Y9FTCQBXfZ8m0hVTEbJkFdjwEAFP1h4kYiLJ5+XiWex3Grur cyeypeq0hwt2wHY5flT3f32PFXvf7FsqbrloTGpVMTPv1TkILt0ttmdRo0aSwzCu8/33 198R/GGucfOxWM3kWcaXyJVHRx3BYeeigtx3kXkM59JoUNaHKy1vuy+fB4G4phJVCVRm v7f+eUWo+703KuvcCjHn3ABBUbyb3zQZEMQxqaz4tjfWJSWCCAqZTAKyn16Uqp1FzIgf rF/KD6C5RFJgmxg7LNUUuzh93pLHT7CU66HPvXF208JlZZ39qG3ERE6Sb/8vd+EtQrWA 52NA== X-Received: by 10.42.93.84 with SMTP id w20mr8370065icm.49.1405901970876; Sun, 20 Jul 2014 17:19:30 -0700 (PDT) MIME-Version: 1.0 Sender: kay21s@gmail.com Received: by 10.64.206.166 with HTTP; Sun, 20 Jul 2014 17:19:09 -0700 (PDT) In-Reply-To: <59AF69C657FD0841A61C55336867B5B0343B0A39@IRSMSX103.ger.corp.intel.com> References: <59AF69C657FD0841A61C55336867B5B0343B0A39@IRSMSX103.ger.corp.intel.com> From: Kai Zhang Date: Sun, 20 Jul 2014 20:19:09 -0400 X-Google-Sender-Auth: CJzsamJnVz7y_TUlEZioxnypkhw Message-ID: To: "Richardson, Bruce" Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] Running independent processes on the same machine 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: Mon, 21 Jul 2014 00:18:20 -0000 Hi Bruce, Thanks for your help. I have implemented rx and tx in the same program to measure round trip latency. 2 machines (A and B) are connected back-to-back with Intel 82599 NIC. Machine A embeds a time stamp in the packet and sends to B, B (use testpmd or l2fwd) forwards packets back to A immediately (A->B->A), and A receives packets and calculates time difference between current time and the embedded time stamp. (code : https://github.com/kay21s/dpdk/tree/master/examples/recv_send) I got an average of 650~720 microseconds round-trip latency. I have 3 machines, and performing the above experiment on each pair leads to a similar latency. However, previous academic papers report that DPDK offers only a few 10 microseconds round trip latency. What's the round trip latency DPDK is supposed to offer? Have you measured it at Intel? Thanks a lot, Kai