Messages in this thread | | | Subject | Re: [RFC PATCH 2/2] sched: idle: IRQ based next prediction for idle period | From | Daniel Lezcano <> | Date | Tue, 12 Jan 2016 13:41:52 +0100 |
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On 01/08/2016 04:43 PM, Thomas Gleixner wrote: > On Wed, 6 Jan 2016, Daniel Lezcano wrote: >> +/** >> + * sched_irq_timing_free - free_irq callback >> + * >> + * @irq: the irq number to stop tracking >> + * @dev_id: not used at the moment >> + * >> + * This function will remove from the wakeup source prediction table. >> + */ >> +static void sched_irq_timing_free(unsigned int irq, void *dev_id) >> +{ >> + struct irq_desc *desc = irq_to_desc(irq); > > What has this code to fiddle with irq_desc? Nothing! > >> + raw_spin_lock_irqsave(&desc->lock, flags); >> + desc->timings = &irq_timings; >> + raw_spin_unlock_irqrestore(&desc->lock, flags); > > Bah, no. This belongs into the core code. Add that handler - and yes, that's > all you need - to your timing_ops and let the core code do it in a proper way.
Ah, yes, you are right. That will be much more cleaner.
>> +/** >> + * sched_idle_init - setup the interrupt tracking table >> + * >> + * At init time, some interrupts could have been setup and in the >> + * system life time, some devices could be setup. In order to track >> + * all interrupts we are interested in, we first register a couple of >> + * callback to keep up-to-date the interrupt tracking table and then >> + * we setup the table with the interrupt which were already set up. >> + */ >> +int __init sched_idle_init(void) >> +{ >> + struct irq_desc *desc; >> + unsigned int irq; >> + int ret; >> + >> + /* >> + * Register the setup/free irq callbacks, so new interrupt or >> + * freed interrupt will update their tracking. >> + */ >> + ret = register_irq_timings(&irqt_ops); >> + if (ret) { >> + pr_err("Failed to register timings ops\n"); >> + return ret; >> + } > > So that stuff is installed unconditionally. Is it used unconditionally as > well?
Sorry, I am not sure to understand your question. If the kernel is compiled with CONFIG_CPU_IDLE_GOV_SCHED=y, this code is enabled and use the irq timings. The condition comes from the compilation option.
Is that your question ?
>> + /* >> + * For all the irq already setup, assign the timing callback. >> + * All interrupts with their desc NULL will be discarded. >> + */ >> + for_each_irq_desc(irq, desc) >> + sched_irq_timing_setup(irq, desc->action); > > No, no, no. This belongs into the core code register_irq_timings() function > which installs the handler into the irq descs with the proper protections and > once it has done that enables the static key.
Ok.
> The above is completely unprotected against interrupts being setup or even > freed concurrently.
Ok, I will do the change.
> Aside of that, you call that setup function in setup_irq for each action() and > here you call it only for the first one.
Ah, right.
Thanks for the review.
-- Daniel
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