From: Julius S. <ju...@zg...> - 2006-03-10 16:47:03
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Hi, I was wondering if it was possible to have multiple UMLs share a single tap device. My goal is to have one subnet on tap0 in which all the UMLs are too, so you get one big virtual ethernet network. I now get 'TUNSETIFF failed, errno = 16' when I try to get the second UML to work though. What am I doing wrong here? What is the recommended way to build a virtual network using UMLs? Thanks in advance, Julius |
From: Jim C. <ji...@ma...> - 2006-03-10 17:12:37
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On Fri, 10 Mar 2006, Julius Schwartzenberg wrote: > I was wondering if it was possible to have multiple UMLs share a single > tap device. My goal is to have one subnet on tap0 in which all the UMLs > are too, so you get one big virtual ethernet network. I doubt it's possible, since each UML needs its own IP address and a shared interface wouldn't know which guest to send packets to. The tunnel driver can spawn arbitrarily many tun/tap devices at little cost; if you can create one, you can create ... I actually don't know the upper bound, but it must be at least 16 and it might even be a module parameter if you need to raise the limit. The host (configured as a router) will do the virtual Ethernet thing as its default behavior. With many guests on one host, remember that the CPU is shared, and if several guests get CPU-intensive at the same time their individual performance will drop off. Also UMLs take a lot of memory; be sure there's enough. James F. Carter Voice 310 825 2897 FAX 310 206 6673 UCLA-Mathnet; 6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA 90095-1555 Email: ji...@ma... http://www.math.ucla.edu/~jimc (q.v. for PGP key) |
From: Julius S. <ju...@zg...> - 2006-03-11 22:09:55
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Jim Carter schreef: > With many guests on one host, remember that the CPU is shared, and if > several guests get CPU-intensive at the same time their individual > performance will drop off. Also UMLs take a lot of memory; be sure there's > enough. Do UMLs really take a lot of extra memory? I'm using a Pentium III 700MHz with 256MB as my host. I was planning to run about 4 UMLs. They won't have very intensive tasks though. Thanks, Julius |
From: Blaisorblade <bla...@ya...> - 2006-03-12 20:25:42
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On Saturday 11 March 2006 23:12, Julius Schwartzenberg wrote: > Jim Carter schreef: > > With many guests on one host, remember that the CPU is shared, and if > > several guests get CPU-intensive at the same time their individual > > performance will drop off. Also UMLs take a lot of memory; be sure > > there's enough. > > Do UMLs really take a lot of extra memory? I'm using a Pentium III > 700MHz with 256MB as my host. I was planning to run about 4 UMLs. They > won't have very intensive tasks though. I usually run UML with 32M of RAM and they don't use it all often (I wouldn't try 16M, but 24M may work); then it comes swap space. Additionally there's the space which is used to cache the UBD, but that can be reduced a bit when you use a common backing file with different COW files on top of it (if the COW file is little, the host can easy notice the content sharing). -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it |
From: Blaisorblade <bla...@ya...> - 2006-03-10 17:39:53
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On Friday 10 March 2006 17:49, Julius Schwartzenberg wrote: > Hi, > > I was wondering if it was possible to have multiple UMLs share a single > tap device. You can, but not the way you're trying. > My goal is to have one subnet on tap0 in which all the UMLs are too, so > you get one big virtual ethernet network. That's possible, but you need to make UML use the daemon transport, and run uml_switch beforehand, connecting it to a pre-setup tap0 device. See the main page for more info (http://user-mode-linux.sourceforge.net/ -> Virtual networking). > I now get 'TUNSETIFF failed, errno = 16' when I try to get the second > UML to work though. That's correct, you can't do it this way, like I said. -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it |
From: Jason L. <lu...@fa...> - 2006-03-10 18:40:08
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bla...@ya... said: >> My goal is to have one subnet on tap0 in which all the UMLs are too, so >> you get one big virtual ethernet network. > > That's possible, but you need to make UML use the daemon transport, and run > uml_switch beforehand, connecting it to a pre-setup tap0 device. See the main > page for more info (http://user-mode-linux.sourceforge.net/ -> Virtual > networking). You can also give each uml its own tap device, then use standard linux bridging to bridge all the taps together on the host. Though I wonder if this method has advantages or disadvantages compared to using the switch daemon. I prefer using "normal" networking as opposed to a special daemon. But maybe it's less efficient or something. Jason |
From: Julius S. <ju...@zg...> - 2006-03-11 22:06:41
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Blaisorblade schreef: > That's possible, but you need to make UML use the daemon transport, and run > uml_switch beforehand, connecting it to a pre-setup tap0 device. See the main > page for more info (http://user-mode-linux.sourceforge.net/ -> Virtual > networking). Thanks for the tip. Seems to be working great :) One thing that wasn't on the page though, is to make sure that all the UMLs are able to access /tmp/uml.ctl. I'm using a UML group for it myself. |
From: Blaisorblade <bla...@ya...> - 2006-03-12 20:27:30
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On Saturday 11 March 2006 23:08, Julius Schwartzenberg wrote: > Blaisorblade schreef: > > That's possible, but you need to make UML use the daemon transport, and > > run uml_switch beforehand, connecting it to a pre-setup tap0 device. See > > the main page for more info (http://user-mode-linux.sourceforge.net/ -> > > Virtual networking). > > Thanks for the tip. Seems to be working great :) > One thing that wasn't on the page though, is to make sure that all the > UMLs are able to access /tmp/uml.ctl. I'm using a UML group for it myself. /tmp is normally world-writable, but if the daemon runs as a different UID than the UMLs, the created socket won't be accessible if you don't change the socket permissions. Made UML crash and found a bug some time ago, by doing this (the fix is now merged, don't worry). -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Messenger with Voice: chiama da PC a telefono a tariffe esclusive http://it.messenger.yahoo.com |
From: frank e. <pri...@gm...> - 2006-03-13 20:26:52
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Similarly to this, I have been running uml_switch with directly specified subnets as follows: uml_switch -unix ./s0 uml_switch -unix ./s1 and so forth, where each of ./s0, ./s1, etc. provide a specific connection. I can then connect various interfaces to the appropriate sockets at start time by specifying eth0=3Ddaemon,,unix,./s0 eth1=3Ddaemon,,unix,./s1 and so forth. So far, I have run a couple of routers in uml, connected through various ports to different subnets, each connected through a specified uml_switch subnet. Best Regards, Ben On 3/12/06, Blaisorblade <bla...@ya...> wrote: > > On Saturday 11 March 2006 23:08, Julius Schwartzenberg wrote: > > Blaisorblade schreef: > > > That's possible, but you need to make UML use the daemon transport, > and > > > run uml_switch beforehand, connecting it to a pre-setup tap0 device. > See > > > the main page for more info (http://user-mode-linux.sourceforge.net/-= > > > > Virtual networking). > > > > Thanks for the tip. Seems to be working great :) > > One thing that wasn't on the page though, is to make sure that all the > > UMLs are able to access /tmp/uml.ctl. I'm using a UML group for it > myself. > > /tmp is normally world-writable, but if the daemon runs as a different UI= D > than the UMLs, the created socket won't be accessible if you don't change > the > socket permissions. > > Made UML crash and found a bug some time ago, by doing this (the fix is > now > merged, don't worry). > -- > Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". > Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ > 215621894) > http://www.user-mode-linux.org/~blaisorblade > > > ___________________________________ > Yahoo! Messenger with Voice: chiama da PC a telefono a tariffe esclusive > http://it.messenger.yahoo.com > > > > ------------------------------------------------------- > This SF.Net email is sponsored by xPML, a groundbreaking scripting > language > that extends applications into web and mobile media. Attend the live > webcast > and join the prime developer group breaking into this new coding > territory! > http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=3D110944&bid=3D241720&dat= =3D121642 > _______________________________________________ > User-mode-linux-user mailing list > Use...@li... > https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user > |