Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [RFC] irq: Skip printing irq when desc->action is null even if any_count is not zero | Date | Wed, 22 Jan 2020 13:42:48 +0100 |
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Chao,
l00520965 <liuchao173@huawei.com> writes:
> When desc->action is empty, there is no need to print out the irq and its' > count in each cpu. The desc is not alloced in request_irq or freed in > free_irq.
request/free_irq() never allocate/free irq descriptors.
> So some PCI devices, such as rtl8139, uses request_irq and free_irq,
All PCI devices use some variant of request_irq()/free_irq(). The interrupt descriptors are allocated by the underlying PCI machinery. They are only allocated/freed when the device driver is loaded/removed.
And this property exists for _ALL_ interrupts independent of PCI.
> which only modify the action of desc. So /proc/interrupts could be > like this:
I think you want to explain:
If an interrupt is released via free_irq() without removing the underlying irq descriptor, the interrupt count of the irq descriptor is not reset. /proc/interrupt shows such interrupts with an empty action handler name:
> CPU0 CPU1 > 38: 46 0 GICv3 36 Level ehci_hcd:usb1 > 39: 66 0 GICv3 37 Level
irqbalance fails to detect that this interrupt is not longer in use and parses the last word in the line 'Level' as the action handler name.
> Irqbalance gets the list of interrupts according to /proc/interrupts. In > this case, irqbalance does not remove the interrupt from the balance list, > and the last string in this line,which is Level, is used as irq_name.
Right, this is historic behaviour and I don't know how irqbalance dealt with that in the past 20+ years. At least I haven't seen any complaints.
I'm not opposed to suppress the output, but I really want the opinion of the irqbalance maintainers on that.
> Or we can clear desc->kstat_irqs in each cpu in free_irq when > desc->action is null?
No, we can't. The historic behaviour is that the total interrupt count for a device is maintained independent of the number of request/free_irq() pairs.
> Signed-off-by: LiuChao <liuchao173@huawei.com> > Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
I really can't remember that I have reviewed this patch already. Please don't add tags which claim that some one has reviewed or acked your patch unless you really got that Reviewed-by or Acked-by from that person.
Thanks,
tglx
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