Hi all, In a physical standar machine, your network limit (in Mbps) depends on several factors (driver, data bus... etc) but one of the main items is the interruptions management. I''m wondering how Xen manages de interrupts, ¿every virtual NIC is trated as a physical NIC? I''ve several dom0s with a domUs (paravirtualitzed) with a lot of network activity as you can get with a busy SMTP server or load-balancer, for example. Monitoring with tools like munin I really see that these busy-networking domUs actually "eat" a lot of RX/TX kbps of physical NIC, but the question stills there ¿how to know the "limit"? Normally your network limit is not established by network traffic (in Mbps): your network limit is established by the amount of packets which means a lot of interruptions. If you recive, for example, a lot af little packets you can get a minimal traffic and, on the other hand, a really busy NIC! ¿How to know the network limits (in interruptions load I mean)? -- Thanks, Jordi Espasa Clofent _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jordi Espasa Clofent
2009-Aug-04 14:07 UTC
Re: [Xen-users] How to know the network limits?
I answer myself: * the network limit (in interruptions sense) is the physical NIC limit, because of all the level 2 happens in dom0. It''s well-documented: http://wiki.xensource.com/xenwiki/XenNetworking#head-842828f687d0a0831c3918127f1860eab52590b9 -- Thanks, Jordi Espasa Clofent _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Tue, Aug 4, 2009 at 9:07 PM, Jordi Espasa Clofent<jespasac@minibofh.org> wrote:> I answer myself: > > * the network limit (in interruptions sense) is the physical NIC limit, > because of all the level 2 happens in dom0.Is it? Last time I check, transfer between domU <-> dom0 (which is all on virtual interfaces, involving vif and bridge) on a somewhat old machine (an old Xeon 3.2 GHz) got me around 1-2 Gbps with 100% CPU usage. So when you have -- say -- a 10Gbps NIC, the physical NIC is no longer the limiting factor. -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jordi Espasa Clofent
2009-Aug-05 10:28 UTC
Re: [Xen-users] How to know the network limits?
Fajar A. Nugraha escribió:> On Tue, Aug 4, 2009 at 9:07 PM, Jordi Espasa > Clofent<jespasac@minibofh.org> wrote: >> I answer myself: >> >> * the network limit (in interruptions sense) is the physical NIC limit, >> because of all the level 2 happens in dom0. > > Is it? > Last time I check, transfer between domU <-> dom0 (which is all on > virtual interfaces, involving vif and bridge) on a somewhat old > machine (an old Xeon 3.2 GHz) got me around 1-2 Gbps with 100% CPU > usage. So when you have -- say -- a 10Gbps NIC, the physical NIC is no > longer the limiting factor.If you make a transfer between domU <-> dom0 you''re using level 3 (IP) but also level 2 (LINK LAYER, localhost). So, _in interruptions sense_ the physical limit is the physical NIC limit. Feel free to correct me if you think my reasoning is wrong. :) -- Thanks, Jordi Espasa Clofent _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users