6.11-stable review patch. If anyone has any objections, please let me know.
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From: Chen Yu yu.c.chen@intel.com
[ Upstream commit 84d265281d6cea65353fc24146280e0d86ac50cb ]
commit 97450eb90965 ("sched/pelt: Remove shift of thermal clock") removed the decay_shift for hw_pressure. This commit uses the sched_clock_task() in sched_tick() while it replaces the sched_clock_task() with rq_clock_pelt() in __update_blocked_others(). This could bring inconsistence. One possible scenario I can think of is in ___update_load_sum():
u64 delta = now - sa->last_update_time
'now' could be calculated by rq_clock_pelt() from __update_blocked_others(), and last_update_time was calculated by rq_clock_task() previously from sched_tick(). Usually the former chases after the latter, it cause a very large 'delta' and brings unexpected behavior.
Fixes: 97450eb90965 ("sched/pelt: Remove shift of thermal clock") Signed-off-by: Chen Yu yu.c.chen@intel.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Hongyan Xia hongyan.xia2@arm.com Reviewed-by: Vincent Guittot vincent.guittot@linaro.org Link: https://lkml.kernel.org/r/20240827112607.181206-1-yu.c.chen@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/fair.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d87e5e95f4a76..1d2cbdb162a67 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9365,9 +9365,10 @@ static bool __update_blocked_others(struct rq *rq, bool *done)
hw_pressure = arch_scale_hw_pressure(cpu_of(rq));
+ /* hw_pressure doesn't care about invariance */ decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) | update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) | - update_hw_load_avg(now, rq, hw_pressure) | + update_hw_load_avg(rq_clock_task(rq), rq, hw_pressure) | update_irq_load_avg(rq, 0);
if (others_have_blocked(rq))