From mboxrd@z Thu Jan 1 00:00:00 1970 From: xuehai zhang Subject: Re: MPI benchmark performance gap between native linux anddomU Date: Tue, 05 Apr 2005 00:27:22 -0500 Message-ID: <425221BA.5030801@cs.uchicago.edu> References: <6C21311CEE34E049B74CC0EF339464B902FB1E@cacexc12.americas.cpqcorp.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <6C21311CEE34E049B74CC0EF339464B902FB1E@cacexc12.americas.cpqcorp.net> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Santos, Jose Renato G (Jose Renato Santos)" Cc: "Turner, Yoshio" , Aravind Menon , Xen-devel@lists.xensource.com, G John Janakiraman List-Id: xen-devel@lists.xenproject.org Jose, Thank you so much for your valueable information. > I guess I overlooked the rates you reported in your post. > Looking now at your rates carefully I got somewhat confused. When you > say MB/sec do you mean Megabyte/sec or Migabit/sec? It is Megabyte/sec (2^20 bytes) > In any case these > are much lower rates than in our case (we were using a gigabit network). > Now, I am starting to think that your problem might be different than > ours, but it does not hurt to try changing the advertised window, just > in case. I will try your suggestion and sent out update tomorrow morning. > Also, the numbers your report are inconsistent. You mention that your > network is 10 MB/s, and that native linux achieve 14.9 MB/s. How is it > possible to achieve a throughput higher than the network bandwidth? > Could you please clarify? Yes, it is a little confusing. It is due to the caculation of SendRecv's throughput. If you take a look at the PMB user manual (following the link in my previous email), the throughput is defined as 2X/1.048567/time (time is latency). So, it is a weighted throughput and could go beyond 10MB/s, which is the max bandwidth of the network. Thanks. Xuehai