On Sat, Oct 07, 2023 at 04:44:46PM +0800, Hao Jia wrote:
That is, would not something like the below make more sense?
If we understand correctly, this may not work.
After applying this patch, the following situation will trigger the rq->clock_update_flags < RQCF_ACT_SKIP warning.
If rq_clock_skip_update() is called before __schedule(), so RQCF_REQ_SKIP of rq->clock_update_flags is set.
__schedule() { rq_lock(rq, &rf); [rq->clock_update_flags is RQCF_REQ_SKIP] rq->clock_update_flags <<= 1; update_rq_clock(rq); [rq->clock_update_flags is RQCF_ACT_SKIP]
- rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
- At this time, rq->clock_update_flags = 0; *
Fixed easily enough, just change to:
rq->clock_updated_flags = RQCF_UPDATED;
pick_next_task_fair set_next_entity update_load_avg assert_clock_updated() <---}
--- diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a0a582c8cf8c..cf9eb1a26c22 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5357,8 +5357,6 @@ context_switch(struct rq *rq, struct task_struct *prev, /* switch_mm_cid() requires the memory barriers above. */ switch_mm_cid(rq, prev, next);
- rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); - prepare_lock_switch(rq, next, rf);
/* Here we just switch the register state and the stack. */ @@ -6596,6 +6594,7 @@ static void __sched notrace __schedule(unsigned int sched_mode) /* Promote REQ to ACT */ rq->clock_update_flags <<= 1; update_rq_clock(rq); + rq->clock_update_flags = RQCF_UPDATED;
switch_count = &prev->nivcsw;
@@ -6675,8 +6674,6 @@ static void __sched notrace __schedule(unsigned int sched_mode) /* Also unlocks the rq: */ rq = context_switch(rq, prev, next, &rf); } else { - rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); - rq_unpin_lock(rq, &rf); __balance_callbacks(rq); raw_spin_rq_unlock_irq(rq);