From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id 68DB89A9C for ; Wed, 25 Mar 2015 18:32:52 +0100 (CET) Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga102.fm.intel.com with ESMTP; 25 Mar 2015 10:32:52 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,466,1422950400"; d="scan'208";a="546232283" Received: from bricha3-mobl3.ger.corp.intel.com ([10.243.20.28]) by orsmga003.jf.intel.com with SMTP; 25 Mar 2015 10:32:49 -0700 Received: by (sSMTP sendmail emulation); Wed, 25 Mar 2015 17:32:48 +0025 Date: Wed, 25 Mar 2015 17:32:48 +0000 From: Bruce Richardson To: Cheng Kevin Message-ID: <20150325173248.GA2824@bricha3-MOBL3> References: <20150325150156.GA5620@bricha3-MOBL3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Shannon Ltd. User-Agent: Mutt/1.5.23 (2014-03-12) Cc: dev@dpdk.org Subject: Re: [dpdk-dev] DPDK testpmd, Virtual Disk IO limitation 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: Wed, 25 Mar 2015 17:32:52 -0000 On Thu, Mar 26, 2015 at 12:20:42AM +0800, Cheng Kevin wrote: > Mr. Bruce Richardson > > Yes, you are right. This really bother me. > > Is there any way to get rid of system call? Maybe some DPDK threading API? > Maybe i should use a extra nic card for posting the data out through > internet, instead of writing on the disk - ex. fwrite. > > Or you have some better advises?? > > Thanks > Kevin > Hi Kevin, what is your end-goal that you are trying to get to? /Bruce > > 2015-03-25 23:01 GMT+08:00 Bruce Richardson : > > > On Wed, Mar 25, 2015 at 10:06:48PM +0800, Cheng Kevin wrote: > > > Hi all, > > > > > > I am a beginner of DPDK. Recently, i am interest in DPDK vHost app - > > > testpmd. > > > > > > And i have been tracing on testpmd.c and iofwd.c for a while. > > > > > > Also add some code inside iofwd.c for storing the payload of packets. > > > > > > Everything goes fine, and the performance is great as expected. > > > > > > But when i use fwrite to store the payload into a file, > > > > > > the performance decrease from 800mbps to 3mbps (input stream is 1 > > Gbps). > > > > > > Is is caused by the limitation of Virtual Disk IO? How can i solve it? > > > > > > I have tried to search the answer, some people say "pthread" might > > solve > > > the problem. > > > > > > Can someone give me some hint, i really appreciate for your help. > > > > > > > > > Best Regard, > > > > > > Kevin Cheng > > > > Two general issues you will hit writing to disk: > > 1) IO, including disk IO, is slow > > 2) System calls are slow. > > > > You are probably hitting both bottlenecks. > > > > /Bruce > >