From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: VMXNET3 on vmware, ping delay Date: Thu, 25 Jun 2015 18:46:30 +0300 Message-ID: <558C2256.4070802@cloudius-systems.com> References: <792CF0A6B0883C45AF8C719B2ECA946E42B2430F@DEMUMBX003.nsn-intra.net> <20150625151834.GA29296@mhcomputing.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: "dev@dpdk.org" To: Matthew Hall , "Vass, Sandor (Nokia - HU/Budapest)" Return-path: Received: from mail-wi0-f173.google.com (mail-wi0-f173.google.com [209.85.212.173]) by dpdk.org (Postfix) with ESMTP id EAAD8C69A for ; Thu, 25 Jun 2015 17:46:32 +0200 (CEST) Received: by wicnd19 with SMTP id nd19so168019972wic.1 for ; Thu, 25 Jun 2015 08:46:32 -0700 (PDT) In-Reply-To: <20150625151834.GA29296@mhcomputing.net> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 06/25/2015 06:18 PM, Matthew Hall wrote: > On Thu, Jun 25, 2015 at 09:14:53AM +0000, Vass, Sandor (Nokia - HU/Budapest) wrote: >> According to my understanding each packet should go >> through BR as fast as possible, but it seems that the rte_eth_rx_burst >> retrieves packets only when there are at least 2 packets on the RX queue of >> the NIC. At least most of the times as there are cases (rarely - according >> to my console log) when it can retrieve 1 packet also and sometimes only 3 >> packets can be retrieved... > By default DPDK is optimized for throughput not latency. Try a test with > heavier traffic. > > There is also some work going on now for DPDK interrupt-driven mode, which > will work more like traditional Ethernet drivers instead of polling mode > Ethernet drivers. > > Though I'm not an expert on it, there is also a series of ways to optimize for > latency, which hopefully some others could discuss... or maybe search the > archives / web site / Intel tuning documentation. > What would be useful is a runtime switch between polling and interrupt modes. This was if the load is load you use interrupts, and as mitigation, you switch to poll mode, until the load drops again.