From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-list2-b.sourceforge.net ([10.3.1.8] helo=sc8-sf-list2.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1BxW3B-0005rh-JZ for user-mode-linux-devel@lists.sourceforge.net; Wed, 18 Aug 2004 12:24:45 -0700 Message-ID: <4123ACEA.6080600@ericsson.com> From: Jon Maloy MIME-Version: 1.0 References: <4123A17A.9070200@americasm01.nt.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Subject: [uml-devel] Re: [tipc-discussion] tipc in networked UML Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Wed, 18 Aug 2004 15:24:26 -0400 To: Randy Macleod Cc: user-mode-linux-devel@lists.sourceforge.net, tipc-discussion@lists.sourceforge.net See below /jon Randy Macleod wrote: > > Hello, > > I'm simulating a small cluster of processors using > UML (user-mode-linux.sourceforge.net) > and TIPC (tipc.sf.net). > Has anyone else tried this? > > The network is simulated using tun devices, i.e. > > cpu0 with eth0 in a UML is connected to pce.0.0.0 > cpu1 with eth0 in a UML is connected to pce.0.1.0 > > A bridge device connects these pce(s) and forwards > ethernet frames based on mac addrs. Packet delivery > is communicated to the UML receiver by a signal according > to Jeff Dike (the UML guy) > > Below is some output of /sbin/ifconfig -a on the desktop... > > Now when these UML's load, a tipc kernel module gets insmod'ed > and things work to first order as expected. > BUT... > Several problems occur: > > 1. Connectionless communication is very unreliable. > (see my previous post for tfsend/tfrecv)) > Only 100's of messages can be exchanged before getting > a sequence error. At least this should make it easier to reproduce and track down the problem you identified in your previous mail... > > > 2. Resetting 1 node causes confusion of the tipc name table > of other nodes. > > If I have 3 UML's (A,B,C), > - publish a tipcname on A, > - reset node C > - then node A get stuck periodically withdrawing the published name. Do you mean node A hangs ? (Btw, are you running the latest version tipc-1.3.14 ?, I fixed a quite nasty bug in one of the later versions, where equal publications from different nodes got the same publication key, with the result that the wrong publication was removed sometimes) > > > > 3. On a lightly loaded system with 10s of processes per UML, > there are frequently very long (> 5 seconds) tipc packet latencies > whereas the normal latency is 0.3 seconds. The desktop load > is always very low. If I ping each node every 0.1 seconds > the high latencies mostly go away. Seem's like the signal > is missed... > > > So, does TIPC assume real-time behaviour > of packets on the network. i.e. by the time N packets have been > sent, the other kernels have received the packets and will send > flow control messages? To work really well we assume that there is real parallelism, but TIPC should never fail because of long latency times. I think I have a seen similar effect on VmWare. > > > If this is the case then I think a minimal modification to UML > to do a sched_yield() every N packets (in or out) would > help matters. Furthermore, it may be a good idea to co-operatively > schedule all the UML's so that their clocks are all in sync and > no node can send or receive too many packets at one time. > > Comments? > > // Randy > > > > > cpbr.0 Link encap:Ethernet HWaddr 00:FF:3A:1A:CB:69 > inet addr:10.0.254.1 Bcast:10.255.255.255 Mask:255.255.0.0 > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 > RX packets:52 errors:0 dropped:0 overruns:0 frame:0 > TX packets:10 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:0 > RX bytes:1624 (1.5 Kb) TX bytes:704 (704.0 b) > > pce.0.0.0 Link encap:Ethernet HWaddr 00:FF:E2:5D:50:B0 > UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 > RX packets:3262 errors:0 dropped:0 overruns:0 frame:0 > TX packets:2562 errors:0 dropped:149 overruns:0 carrier:0 > collisions:0 txqueuelen:1024 > RX bytes:452010 (441.4 Kb) TX bytes:519063 (506.8 Kb) > > pce.0.1.0 Link encap:Ethernet HWaddr 00:FF:3A:1A:CB:69 > UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 > RX packets:6 errors:0 dropped:0 overruns:0 frame:0 > TX packets:1333 errors:0 dropped:1079 overruns:0 carrier:0 > collisions:0 txqueuelen:1024 > RX bytes:228 (228.0 b) TX bytes:302530 (295.4 Kb) > > > > > > ------------------------------------------------------- > SF.Net email is sponsored by Shop4tech.com-Lowest price on Blank Media > 100pk Sonic DVD-R 4x for only $29 -100pk Sonic DVD+R for only $33 > Save 50% off Retail on Ink & Toner - Free Shipping and Free Gift. > http://www.shop4tech.com/z/Inkjet_Cartridges/9_108_r285 > _______________________________________________ > tipc-discussion mailing list > tipc-discussion@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/tipc-discussion ------------------------------------------------------- SF.Net email is sponsored by Shop4tech.com-Lowest price on Blank Media 100pk Sonic DVD-R 4x for only $29 -100pk Sonic DVD+R for only $33 Save 50% off Retail on Ink & Toner - Free Shipping and Free Gift. http://www.shop4tech.com/z/Inkjet_Cartridges/9_108_r285 _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel