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Date:   Tue, 29 Sep 2020 18:46:54 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Bjorn Helgaas <helgaas@kernel.org>
Cc:     Nitesh Narayan Lal <nitesh@redhat.com>, hch@infradead.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
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        jeffrey.t.kirsher@intel.com, jacob.e.keller@intel.com,
        jlelli@redhat.com, bhelgaas@google.com, mike.marciniszyn@intel.com,
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        juri.lelli@redhat.com, vincent.guittot@linaro.org,
        lgoncalv@redhat.com
Subject: Re: [PATCH v4 4/4] PCI: Limit pci_alloc_irq_vectors() to
 housekeeping CPUs
Message-ID: <20200929174654.GA773@infradead.org>
References: <20200928183529.471328-5-nitesh@redhat.com>
 <20200928215931.GA2499944@bjorn-Precision-5520>
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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@lst.de>