Messages in this thread | | | Date | Tue, 22 May 2018 16:26:24 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH v2] schedutil: Allow cpufreq requests to be made even when kthread kicked |
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On 22-05-18, 11:51, Patrick Bellasi wrote: > It could happen, but using: > > raw_spin_lock_irqsave(&sg_policy->update_lock, flags); > freq = READ_ONCE(sg_policy->next_freq) > WRITE_ONCE(sg_policy->work_in_progress, false); > raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags); > > if (!READ_ONCE(sg_policy->work_in_progress)) { > WRITE_ONCE(sg_policy->work_in_progress, true); > irq_work_queue(&sg_policy->irq_work); > }
I think its better to get locking in place for non-fast switching case in single-policy systems right now.
> should fix it by enforcing the ordering as well as documenting the > concurrent access. > > However, in the "sched update" side, where do we have the sequence: > > sg_policy->next_freq = 0; > sg_policy->next_freq = real-next-freq;
Ah, that was just an example of what a compiler may do (though it shouldn't do).
-- viresh
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