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author | Vincent Guittot <vincent.guittot@linaro.org> | 2021-05-27 14:29:16 +0200 |
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committer | Peter Zijlstra <peterz@infradead.org> | 2021-05-31 10:14:48 +0200 |
commit | 02da26ad5ed6ea8680e5d01f20661439611ed776 (patch) | |
tree | 495173532ac8f5da060d592d618edae82fd37e72 /block/blk-integrity.c | |
parent | sched/fair: Keep load_avg and load_sum synced (diff) | |
download | linux-02da26ad5ed6ea8680e5d01f20661439611ed776.tar.xz linux-02da26ad5ed6ea8680e5d01f20661439611ed776.zip |
sched/fair: Make sure to update tg contrib for blocked load
During the update of fair blocked load (__update_blocked_fair()), we
update the contribution of the cfs in tg->load_avg if cfs_rq's pelt
has decayed. Nevertheless, the pelt values of a cfs_rq could have
been recently updated while propagating the change of a child. In this
case, cfs_rq's pelt will not decayed because it has already been
updated and we don't update tg->load_avg.
__update_blocked_fair
...
for_each_leaf_cfs_rq_safe: child cfs_rq
update cfs_rq_load_avg() for child cfs_rq
...
update_load_avg(cfs_rq_of(se), se, 0)
...
update cfs_rq_load_avg() for parent cfs_rq
-propagation of child's load makes parent cfs_rq->load_sum
becoming null
-UPDATE_TG is not set so it doesn't update parent
cfs_rq->tg_load_avg_contrib
..
for_each_leaf_cfs_rq_safe: parent cfs_rq
update cfs_rq_load_avg() for parent cfs_rq
- nothing to do because parent cfs_rq has already been updated
recently so cfs_rq->tg_load_avg_contrib is not updated
...
parent cfs_rq is decayed
list_del_leaf_cfs_rq parent cfs_rq
- but it still contibutes to tg->load_avg
we must set UPDATE_TG flags when propagting pending load to the parent
Fixes: 039ae8bcf7a5 ("sched/fair: Fix O(nr_cgroups) in the load balancing path")
Reported-by: Odin Ugedal <odin@uged.al>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Odin Ugedal <odin@uged.al>
Link: https://lkml.kernel.org/r/20210527122916.27683-3-vincent.guittot@linaro.org
Diffstat (limited to 'block/blk-integrity.c')
0 files changed, 0 insertions, 0 deletions