Messages in this thread |  | | | Date | Thu, 8 Sep 2005 00:23:23 -0700 | | From | Paul Jackson <> | | Subject | Re: [PATCH 0/5] SUBCPUSETS: a resource control functionality using CPUSETS |
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[ Adding Dinakar to explicit cc list, since I mention his work. Hopefully he can correct any mispresentations of his work I might have presented. - pj ]
I've just started reading this - it seems well presented and I think you have put much effort into it. Thank-you for posting it.
I have not yet taken the time to understand it properly, but a couple of questions come to mind offhand. I hope these questions will not be too silly.
1) What is the relation of this patch set to CKRM?
2) Would a structure similar to Dinakar's patches to connect cpusets and dynamic sched domains (posted to linux-mm) work here as well?
Let me describe what I see so far, and hope you will be patient with my confusions. Then perhaps I can better explain my question (2) above.
My initial understanding is that subcpusets provide a way to partial out the proportion of cpu and memory used by various tasks. A leaf node cpuset can partition the tasks attached to it into subsets, called subcpusets, where each subcpuset gets a proportion of cpu and memory available to the original leaf node cpuset.
These original leaf node cpusets (the parents of the 'subcpusets') form a non-overlapping and partial covering of the cpus and memory nodes in a system. It is a _partial_ covering because not every leaf node cpuset need be subdivided into 'subcpusets', nor does every cpu or memory node need to be in such a cpuset.
I'm guessing you do not want such cpusets (the parents of subcpusets) to overlap, because if they did, it would seem to confuse the meaning of getting a fixed proportion of available cpu and memory resources. I was a little surprised not to see any additional checks that cpu_exclusive and mem_exclusive must be set true in these cpusets, to insure non- overlapping cpusets.
Dinakar's patches used cpu_exclusive cpusets to form a complete non-overlapping covering of the cpus in a system (the cpus not in cpu_exclusive cpusets got their own separate covers). Then each such cover defined a different dynamic sched domain (a separately scheduled set of tasks).
Your cover elements (your subcpusets) seem to be a somewhat new kind of cpuset, that can only occur as children of original leaf node cpusets.
Instead of that, I might prefer doing as Dinakar did, and use a single boolean flag per existing cpuset, to mark a subset of the cpusets that form the covering. Dinakar got lucky, and was able to use an existing cpuset boolean flag - cpu_exclusive, which had not been very useful until then. You will have to add a new flag.
On the other hand, Dinakar had more work to do than you might, because he needed a complete covering (so had to round up cpus in non exclusive cpusets to form more covering elements). From what I can tell, you don't need a complete covering - it seems fine if some cpus are not managed by this resource control function.
I hope my above remarks are not to far off the mark and do not misrepresent your work too painfully. And I hope they make at least a little sense. Sometimes I have a strange way of describing my thoughts.
Thank-you again for this good work. I look forward to your further considerations. I will make the time soon to read this patch more closely.
-- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <pj@sgi.com> 1.925.600.0401 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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