Ensure that the move of a sched_entity will be reflected in load and utilization of the task_group hierarchy.
When a sched_entity moves between groups or CPUs, load and utilization of cfs_rq don't reflect the changes immediately but converge to new values. As a result, the metrics are no more aligned with the new balance of the load in the system and next decisions will have a biased view.
This patchset synchronizes load/utilization of sched_entity with its child cfs_rq (se->my-q) only when tasks move to/from child cfs_rq: -move between task group -migration between CPUs Otherwise, PELT is updated as usual.
This version doesn't include any changes related to discussion that have started during the review of the previous version about: - encapsulate the sequence for changing the propoerty of a task - remove a cfs_rq from list during update_blocked_averages These topics don't gain anything from being added in this patchset as they are fairly independent and deserve a separate patch.
Changes since v3: - Replaced the 2 arguments of update_load_avg by 1 flags argument - Propagated move in runnable_load_avg when sched_entity is already on_rq - Ensure that intermediate value will not reach memory when updating load and utilization - Optimize the the calculation of load_avg of the sched_entity - Fixed some typo
Changes since v2: - Propagate both utilization and load - Synced sched_entity and se->my_q instead of adding the delta
Changes since v1: - This patch needs the patch that fixes issue with rq->leaf_cfs_rq_list "sched: fix hierarchical order in rq->leaf_cfs_rq_list" in order to work correctly. I haven't sent them as a single patchset because the fix is independent of this one - Merge some functions that are always used together - During update of blocked load, ensure that the sched_entity is synced with the cfs_rq applying changes - Fix an issue when task changes its cpu affinity Vincent Guittot (7): sched: factorize attach entity sched: fix hierarchical order in rq->leaf_cfs_rq_list sched: factorize PELT update sched: propagate load during synchronous attach/detach sched: propagate asynchrous detach sched: fix task group initialization sched: fix wrong utilization accounting when switching to fair class
kernel/sched/core.c | 21 +-- kernel/sched/fair.c | 354 +++++++++++++++++++++++++++++++++++++++++---------- kernel/sched/sched.h | 2 + 3 files changed, 300 insertions(+), 77 deletions(-)