Messages in this thread | | | Date | Thu, 28 Sep 2006 22:55:20 +0530 | From | Srivatsa Vaddagiri <> | Subject | [RFC, PATCH 0/9] CPU Controller V2 |
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Here's V2 of the token-based CPU controller I have been working on.
Changes since last version (posted at http://lkml.org/lkml/2006/8/20/115):
- Task load was not changed when it moved between task-groups of different quota (bug hit by Mike Galbraith).
- SMP load balance seems to work -much- better now wrt its awaress of quota on each task-group. The trick was to go beyond the max_load difference in __move_tasks and instead use the load difference between two task-groups on the different cpus as basis of pulling tasks.
- Better timeslice management, aimed at handling bursty workloads better. Patch 3/9 has documentation on timeslice management for various task-groups.
- Modified cpuset interface as per Paul Jackson's suggestions. Some of the changes are: - s/meter_cpu/cpu_meter_enabled - s/cpu_quota/cpu_meter_quota - s/FILE_METER_FLAG/FILE_CPU_METER_ENABLED - s/FILE_METER_QUOTA/FILE_CPU_METER_QUOTA - Dont allow cpu_meter_enabled to be turned on for an "in-use" cpuset (which has tasks attached to it) - Dont allow cpu_meter_quota to be changed for an "in-use" cpuset (which has tasks attached to it)
Last two are temporary limitations until we figure out how to get to a cpuset's task-list more easily.
Still on my todo list:
- Improved surplus cycles management. If A, B and C groups have been given 50%, 30% and 20% quota respectively and if group B is idle, B's quota has to be divided b/n A and C in the 5:2 proportion.
- Although load balance seems to be working nicely for the testcases I have been running, I anticipate certain corner cases which are yet to be worked out. Especially I need to make sure some of the HT/MC optimizations are not broken.
Ingo/Nick, IMHO virtualizing cpu-runqueues approach to solve the controller need is not a good idea, since:
- retaining existing load-balance optimizations for MC/SMT case is going to be hard (has to be done at schedule time now) - because of virtualization, two virtual cpus could end up running on the same physical cpu which would affect the carefull SMP optimizations put in place are all-over the kernel - not to mention specialized apps which want to bind to CPUs for performance reasons may behave badly in such a virtualized environment.
Hence I have been pursuing more simpler approaches like in this patch.
Your comments/views on this are highly appreciated.
-- Regards, vatsa - 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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