On Mon, Jan 06, 2014 at 04:34:04PM +0000, Waskiewicz Jr, Peter P wrote: > On Mon, 2014-01-06 at 12:16 +0100, Peter Zijlstra wrote: > > On Sun, Jan 05, 2014 at 05:23:07AM +0000, Waskiewicz Jr, Peter P wrote: > > > The CPU side is easy and clean. When something in the software wants to > > > monitor when a particular task is scheduled and started, write whatever > > > RMID that task is assigned to (through some mechanism) to the proper MSR > > > in the CPU. When that task is swapped out, clear the MSR to stop > > > monitoring of that RMID. When that RMID's statistics are requested by > > > the software (through some mechanism), then the CPU's MSRs are written > > > with the RMID in question, and the value is read of what has been > > > collected so far. In my case, I decided to use a cgroup for this > > > "mechanism" since so much of the grouping and task/group association > > > already exists and doesn't need to be rebuilt or re-invented. > > > > This still doesn't explain why you can't use perf-cgroup for this. > > I'm not completely familiar with perf-cgroup, so I looked for some > documentation for it to better understand it. Are you referring to perf > -G to monitor an existing cgroup/all cgroups? Or something else? If > it's the former, I'm not following you how this would fit. All the bits under CONFIG_CGROUP_PERF, I've no idea how userspace looks. > > > > In general, I'm quite strongly opposed against using cgroup as > > > > arbitrary grouping mechanism for anything other than resource control, > > > > especially given that we're moving away from multiple hierarchies. > > > > > > Just to clarify then, would the mechanism in the cpuacct cgroup to > > > create a group off the root subsystem be considered multi-hierarchical? > > > If not, then the intent for this new cacheqos subsystem is to be > > > identical in that regard to cpuacct in the behavior. > > > > > > This is a resource controller, it just happens to be tied to a hardware > > > resource instead of an OS resource. > > > > No, cpuacct and perf-cgroup aren't actually controllers at all. They're > > resource monitors at best. Same with your Cache QoS Monitor, it doesn't > > control anything. > > I may be using controller in a different way than you are. Yes, the > Cache QoS Monitor is monitoring cache data. But it is also controlling > the allocation and deallocation of RMIDs to tasks/task groups as > monitoring is enabled and disabled for those groups. That's why I > called it a controller. If that's not accurate, I apologize. Yeah that's not accurate, nor desired I think, because you get into horrible problems with hierarchies, do child groups belong to your RMID or not? As is I don't really see a good use for RMIDs and I would simply not use them. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
