{"push_id":1344569376,"size":1,"distinct_size":1,"ref":"refs/heads/prog","head":"f876eaed612794a69db1f81dc0266befa0012770","before":"3aab093b61a6361fd66e11ba57ed7bb20a2ae004","commits":[{"sha":"f876eaed612794a69db1f81dc0266befa0012770","author":{"name":"Paul Walmsley","email":"7951b4c52b27ff0db464091d8a401e79e1809fa3@nvidia.com"},"message":"sched: reinitialize rq->next_balance when a CPU is hot-added\n\nReinitialize rq->next_balance when a CPU is hot-added.  Otherwise,\nscheduler domain rebalancing may be skipped if rq->next_balance was\nset to a future time when the CPU was last active, and the\nnewly-re-added CPU is in idle_balance().  As a result, the\nnewly-re-added CPU will remain idle with no tasks scheduled until the\nsoftlockup watchdog runs - potentially 4 seconds later.  This can\nwaste energy and reduce performance.\n\nThis behavior can be observed in some SoC kernels, which use CPU\nhotplug to dynamically remove and add CPUs in response to load.  In\none case that triggered this behavior,\n\n0. the system started with all cores enabled, running multi-threaded\n   CPU-bound code;\n\n1. the system entered some single-threaded code;\n\n2. a CPU went idle and was hot-removed;\n\n3. the system started executing a multi-threaded CPU-bound task;\n\n4. the CPU from event 2 was re-added, to respond to the load.\n\nThe time interval between events 2 and 4 was approximately 300\nmilliseconds.\n\nOf course, ideally CPU hotplug would not be used in this manner,\nbut this patch does appear to fix a real bug.\n\nNvidia folks: this patch is submitted as at least a partial fix for\nbug 1243368 (\"[sched] Load-balancing not happening correctly after\ncores brought online\")\n\nChange-Id: Iabac21e110402bb581b7db40c42babc951d378d0\nSigned-off-by: Paul Walmsley <pwalmsley@nvidia.com>\nCc: Peter Boonstoppel <pboonstoppel@nvidia.com>\nReviewed-on: http://git-master/r/206918\nReviewed-by: Automatic_Commit_Validation_User\nReviewed-by: Amit Kamath <akamath@nvidia.com>\nGVS: Gerrit_Virtual_Submit\nReviewed-by: Peter Boonstoppel <pboonstoppel@nvidia.com>\nReviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>","distinct":true,"url":"https://api.github.com/repos/tunturn/android_kernel_aries_concept/commits/f876eaed612794a69db1f81dc0266befa0012770"}]}
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