On Tue, Sep 15, 2009 at 11:01:52AM -0700, Alexander Duyck wrote: > Or Gerlitz wrote: > >If the rate limiter is exposed as a feature of the VF, it doesn't > >matter who really enforces it, the "VF portion" of the HW or the > >PF itself. I agree that if you have to program the PF for the rate > >of a specific VF, then its more complex. Basically, I would expect > >that a VF can be configured with <mac, vlad-id, priority, rate> > >such that it can be done where the VF NIC is spawned, host kernel > >or guest kernel. > > Adding the rate limiter as a feature of the VF doesn't make much > sense since the VF could be direct assigned to another OS for all we > know so we won't have control over it from there. > > The interface for all of this would make sense as part of a virtual > ethernet switch control which is the way I am currently leaning on > all this. As such it is probably another thing we can bring up at > the BOF session at the Linux Plumbers Conference.
Unfortunately I won't be able to make it to the BOF or Plumbers. I look forward to hearing what is discussed. > >I'm was asking/wondering if the Intel NICs have a rate limiter > >(i.e one can program the VF such that its rate doesn't exceed XX > >MB/s) or a "rate guarantee" (i.e one can program the VF such that > >its guaranteed it will get YY MB/s in case it wants to xmit at > >least this bandwidth) > > Based on the way I am reading the documentation I would say the all > these registers do is guarantee a minimum percentage of the > bandwidth. With these registers set you can repartition the traffic > so that a percentage can be guaranteed to the PF/VFs if needed. It > works very similar to how DCB allows you to guarantee a certain > amount of bandwidth for each of the traffic classes. However any > time the full tx bandwidth is not being used it will be reallocated > to the other queues and then end up back in the default behavior. > > The default behavior is to DMA descriptors from the rings in a round > robin fashion. Since this effectively guarantees that there will be > packets being pulled off the rings I didn't really feel the > necessity to add the additional overhead of doing this on a per > PF/VF bandwidth basis. My reading of the documentation is also that its a minimum percentage of bandwidth. But after playing with the registers a bit it seems that it is actually a ceiling expressed. And the percentage is of 1Gigabit, regardless of the actual link speed. ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ E1000-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/e1000-devel
