Yunfeng Ye <yeyunf...@huawei.com> writes:
> The "managed_irq" for isolcpus is supported after the commit
> 11ea68f553e2 ("genirq, sched/isolation: Isolate from handling managed
> interrupts"), but the interrupt affinity shown in proc directory is
> still the original affinity.
>
> So modify the interrupt affinity correctly for managed_irq.
I really have no idea what you are trying to achieve here.
1) Why are you moving the !chip !chip->irq_set_affinity check out of
irq_do_set_affinity() ?
Just that the whole computation happens for nothing and then returns
an error late.
2) Modifying irqdata->common->affinity is wrong to begin with. It's the
possible affinity mask. Your change causes the managed affinity mask
to become invalid in the worst case.
irq->affinity = 0x0C; // CPU 2 - 3
hkmask = 0x07; // CPU 0 - 2
Invocation #1:
online_mask = 0xFF; // CPU 0 - 7
cpumask_and(&tmp_mask, mask, hk_mask);
--> tmp_mask == 0x04 // CPU 2
irq->affinity = tmp_mask; // CPU 2
CPU 2 goes offline
migrate_one_irq()
affinity = irq->affinity; // CPU 2
online_mask = 0xFB; // CPU 0-1, 3-7
if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
/*
* If the interrupt is managed, then shut it down and leave
* the affinity untouched.
*/
if (irqd_affinity_is_managed(d)) {
irqd_set_managed_shutdown(d);
irq_shutdown_and_deactivate(desc);
return false;
}
So the interrupt is shut down which is incorrect. The isolation
logic in irq_do_set_affinity() was clearly designed to prefer
housekeeping CPUs and not to remove them.
You are looking at the wrong file. /proc/irq/$IRQ/smp_affinity* is the
possible mask. If you want to know to which CPU an interrupt is affine
then look at /proc/irq/$IRQ/effective_affinity*
If effective_affinity* is not showing the correct value, then the irq
chip affinity setter is broken and needs to be fixed.
Thanks,
tglx
