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From:   Yongji Xie <xieyongji@bytedance.com>
Date:   Mon, 19 Dec 2022 17:36:02 +0800
Message-ID: <CACycT3utDJFZtWzqCUXJaqRjkCXPMTAi+VJd3g6dw25vWqaduw@mail.gmail.com>
Subject: Re: [PATCH v2 01/11] genirq/affinity:: Export irq_create_affinity_masks()
To:     "Michael S. Tsirkin" <mst@redhat.com>,
        Christoph Hellwig <hch@lst.de>
Cc:     Jason Wang <jasowang@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        virtualization <virtualization@lists.linux-foundation.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Mon, Dec 19, 2022 at 3:33 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Dec 05, 2022 at 04:41:17PM +0800, Xie Yongji wrote:
> > Export irq_create_affinity_masks() so that some modules
> > can make use of it to implement interrupt affinity
> > spreading mechanism.
> >
> > Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
>
> So this got nacked, what's the plan now?
>

I=E2=80=98d like to check with Christoph again first.

Hi Christoph,

Jason will post some patches to get rid of the DMA API for vDPA
simulators. And the irq affinity algorithm is independent of the IRQ
subsystem IIUC. So could you allow this patch so that we can reuse the
algorithm to select the best CPU (per-cpu affinity if possible, or at
least per-node) to run the virtqueue's irq callback.

Thanks,
Yongji

> > ---
> >  kernel/irq/affinity.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> > index d9a5c1d65a79..f074a7707c6d 100644
> > --- a/kernel/irq/affinity.c
> > +++ b/kernel/irq/affinity.c
> > @@ -487,6 +487,7 @@ irq_create_affinity_masks(unsigned int nvecs, struc=
t irq_affinity *affd)
> >
> >       return masks;
> >  }
> > +EXPORT_SYMBOL_GPL(irq_create_affinity_masks);
> >
> >  /**
> >   * irq_calc_affinity_vectors - Calculate the optimal number of vectors
> > --
> > 2.20.1
>