* Avi Kivity <avi@xxxxxxxxxx> [2009-06-05 07:44:27]: > Balbir Singh wrote: >> On Fri, Jun 5, 2009 at 11:33 AM, Avi Kivity <avi@xxxxxxxxxx> wrote: >> >>> Bharata B Rao wrote: >>> >>>>> Another way is to place the 8 groups in a container group, and limit >>>>> that to 80%. But that doesn't work if I want to provide guarantees to >>>>> several groups. >>>>> >>>>> >>>> Hmm why not ? Reduce the guarantee of the container group and provide >>>> the same to additional groups ? >>>> >>>> >>> This method produces suboptimal results: >>> >>> $ cgroup-limits 10 10 0 >>> [50.0, 50.0, 40.0] >>> >>> I want to provide two 10% guaranteed groups and one best-effort group. >>> Using the limits method, no group can now use more than 50% of the >>> resources. However, having the first group use 90% of the resources does >>> not violate any guarantees, but it not allowed by the solution. >>> >>> >> >> How, it works out fine in my calculation >> >> 50 + 40 for G2 and G3, make sure that G1 gets 10%, since others are >> limited to 90% >> 50 + 40 for G1 and G3, make sure that G2 gets 10%, since others are >> limited to 90% >> 50 + 50 for G1 and G2, make sure that G3 gets 0%, since others are >> limited to 100% >> > > It's fine in that it satisfies the guarantees, but it is deeply > suboptimal. If I ran a cpu hog in the first group, while the other two > were idle, it would be limited to 50% cpu. On the other hand, if it > consumed all 100% cpu it would still satisfy the guarantees (as the > other groups are idle). > > The result is that in such a situation, wall clock time would double > even though cpu resources are available. But then there is no other way to make a *guarantee*, guarantees come at a cost of idling resources, no? Can you show me any other combination that will provide the guarantee and without idling the system for the specified guarantees? >> Now if we really have zeros, I would recommend using >> >> cgroup-limits 10 10 and you'll see that you'll get 90, 90 as output. >> >> Adding zeros to the calcuation is not recommended. Does that help? > > What do you mean, it is not recommended? I have two groups which need at > least 10% and one which does not need any guarantee, how do I express it? > Ignore this part of my comment > In any case, changing the zero to 1% does not materially change the results. True. -- Balbir -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
