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由 Rik van Riel 提交于
Currently update_sd_pick_busiest only identifies the busiest sd that is either overloaded, or has a group imbalance. When no sd is imbalanced or overloaded, the load balancer fails to find the busiest domain. This breaks load balancing between domains that are not overloaded, in the !SD_ASYM_PACKING case. This patch makes update_sd_pick_busiest return true when the busiest sd yet is encountered. Groups are ranked in the order overloaded > imbalanced > other, with higher ranked groups getting priority even when their load is lower. This is necessary due to the possibility of unequal capacities and cpumasks between domains within a sched group. Behaviour for SD_ASYM_PACKING does not seem to match the comment, but I have no hardware to test that so I have left the behaviour of that code unchanged. Enum for group classification suggested by Peter Zijlstra. Signed-off-by: NRik van Riel <riel@redhat.com> [peterz: replaced sg_lb_stats::group_imb with the new enum group_type in an attempt to avoid endless recalculation] Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Acked-by: NVincent Guittot <vincent.guittot@linaro.org> Acked-by: NMichael Neuling <mikey@neuling.org> Cc: ktkhai@parallels.com Cc: tim.c.chen@linux.intel.com Cc: nicolas.pitre@linaro.org Cc: jhladky@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140729152743.GI3935@laptopSigned-off-by: NIngo Molnar <mingo@kernel.org>
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