Messages in this thread | | | Date | Wed, 22 Jan 2020 14:28:56 -0500 | From | Neil Horman <> | Subject | Re: [RFC] irq: Skip printing irq when desc->action is null even if any_count is not zero |
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On Wed, Jan 22, 2020 at 01:42:48PM +0100, Thomas Gleixner wrote: > 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. > Actually, irqbalance ignores the trailing irq name (or it should at least), so you should be able to drop that portion of /proc/irqbalance, though I cant speak for any other users of it.
> > 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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