Chris Friesen wrote: > Srivatsa Vaddagiri wrote: > >>>> - Support limit (soft and/or hard depending on the resource >>>> type) in controllers. Guarantee feature could be indirectly >>>> met thr limits. > > I just thought I'd weigh in on this. As far as our usage pattern is > concerned, guarantees cannot be met via limits. > > I want to give "x" cpu to container X, "y" cpu to container Y, and "z" > cpu to container Z. > > If these are percentages, x+y+z must be less than 100. > > However, if Y does not use its share of the cpu, I would like the > leftover cpu time to be made available to X and Z, in a ratio based on > their allocated weights. > > With limits, I don't see how I can get the ability for containers to > make opportunistic use of cpu that becomes available. This is basically how "cpuunits" in OpenVZ works. It is not limiting a container in any way, just assigns some relative "units" to it, with sum of all units across all containers equal to 100% CPU. Thus, if we have cpuunits 10, 20, and 30 assigned to containers X, Y, and Z, and run some CPU-intensive tasks in all the containers, X will be given 10/(10+20+30), or 20% of CPU time, Y -- 20/50, i.e. 40%, while Z gets 60%. Now, if Z is not using CPU, X will be given 33% and Y -- 66%. The scheduler used is based on a per-VE runqueues, is quite fair, and works fine and fair for, say, uneven case of 3 containers on a 4 CPU box.
OpenVZ also has a "cpulimit" resource, which is, naturally, a hard limit of CPU usage for a VE. Still, given the fact that cpunits works just fine, cpulimit is rarely needed -- makes sense only in special scenarios where you want to see how app is run on a slow box, or in case of some proprietary software licensed per CPU MHZ, or smth like that. Looks like this is what you need, right? > I can see that with things like memory this could become tricky (How > do you free up memory that was allocated to X when Y decides that it > really wants it after all?) but for CPU I think it's a valid scenario. Yes, CPU controller is quite different of other resource controllers. Kir. ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ ckrm-tech mailing list https://lists.sourceforge.net/lists/listinfo/ckrm-tech
