Re: [PATCH] device-dax: use fallback nid when numa_node is invalid

[David Hildenbrand]

On 29.07.21 16:44, Justin He wrote:
> Hi David
>
> > -----Original Message-----
> > From: David Hildenbrand <david@xxxxxxxxxx>
> > Sent: Thursday, July 29, 2021 3:59 PM
> > To: Justin He <Justin.He@xxxxxxx>; Dan Williams <dan.j.williams@xxxxxxxxx>;
> > Vishal Verma <vishal.l.verma@xxxxxxxxx>; Dave Jiang <dave.jiang@xxxxxxxxx>
> > Cc: nvdimm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; nd <nd@xxxxxxx>
> > Subject: Re: [PATCH] device-dax: use fallback nid when numa_node is
> > invalid
> >
> > Hi Justin,
> >
> > > > >
> > > >
> > > > Note that this patch conflicts with:
> > > >
> > > > https://lkml.kernel.org/r/20210723125210.29987-7-david@xxxxxxxxxx
> > > >
> > > > But nothing fundamental. Determining a single NID is similar to how I'm
> > > > handling it for ACPI:
> > > >
> > > > https://lkml.kernel.org/r/20210723125210.29987-6-david@xxxxxxxxxx
> > >
> > > Okay, got it. Thanks for the reminder.
> > > Seems my patch is not useful after your patch.
> >
> > I think your patch still makes sense. With
> >
> > https://lore.kernel.org/linux-acpi/20210723125210.29987-7-
> > david@xxxxxxxxxx/
> >
> > We'd have to detect the node id in the first loop instead.
>
> Ok, I got your point. I will do that in v2.
>
> Btw, sorry for commenting there about your patch 06 since I didn't
> subscribe lkml via this mailbox.

Sure, you really should subscribe :)

> > +	for (i = 0; i < dev_dax->nr_range; i++) {
> +		struct range range;
> +
> +		rc = dax_kmem_range(dev_dax, i, &range);
> +		if (rc) {
> +			dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
> +					i, range.start, range.end);
> +			continue;
> +		}
> +		total_len += range_len(&range);
> +	}
> You add an additional loop to get the total_len.
> I wonder is it independent on 2nd loop?
> If yes, why not merge the 2 loops into one?
> Sorry if this question is too simple, I don't know too much
> about the background of your patch.

We need total_len to register the memory group. We need the memory group 
to add memory. Therefore, we need a second loop to calculate total_len 
upfront.


--
Thanks,

David / dhildenb