[Intel-wired-lan] [PATCH v4 4/4] PCI: Limit pci_alloc_irq_vectors() to housekeeping CPUs

Christoph Hellwig hch at infradead.org
Tue Sep 29 17:46:54 UTC 2020


On Mon, Sep 28, 2020 at 04:59:31PM -0500, Bjorn Helgaas wrote:
> [to: Christoph in case he has comments, since I think he wrote this code]

I think I actually suggested this a few iterations back.

> > +	hk_cpus = housekeeping_num_online_cpus(HK_FLAG_MANAGED_IRQ);
> > +
> > +	/*
> > +	 * If we have isolated CPUs for use by real-time tasks, to keep the
> > +	 * latency overhead to a minimum, device-specific IRQ vectors are moved
> > +	 * to the housekeeping CPUs from the userspace by changing their
> > +	 * affinity mask. Limit the vector usage to keep housekeeping CPUs from
> > +	 * running out of IRQ vectors.
> > +	 */
> > +	if (hk_cpus < num_online_cpus()) {

I woukd have moved the assignment to hk_cpus below the comment and
just above the if, but that is really just a minor style preference.

Otherwise this looks good:

Acked-by: Christoph Hellwig <hch at lst.de>


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