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From: Rob Herring <robh@kernel.org>
To: Gavin Shan <gshan@redhat.com>
Cc: devicetree@vger.kernel.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	linux-efi <linux-efi@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	"open list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" 
	<kvmarm@lists.cs.columbia.edu>, Marc Zyngier <maz@kernel.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	shan.gavin@gmail.com
Subject: Re: [PATCH v2 2/2] of, numa: Fetch empty NUMA node ID from distance map
Date: Tue, 28 Sep 2021 12:22:08 -0500	[thread overview]
Message-ID: <CAL_JsqJtckde=Ngfhr7u3f_xsccavo+4Pt-v9o_nGHTX+wD91w@mail.gmail.com> (raw)
In-Reply-To: <c101363f-1de7-1d56-a8d9-243f003b48c1@redhat.com>

On Mon, Sep 27, 2021 at 6:59 PM Gavin Shan <gshan@redhat.com> wrote:
>
> Hi Rob,
>
> On 9/28/21 12:49 AM, Rob Herring wrote:
> > On Mon, Sep 27, 2021 at 1:42 AM Gavin Shan <gshan@redhat.com> wrote:
> >>
> >> There is no device node for the empty NUMA node. However, the
> >> corresponding NUMA node ID and distance map is still valid in
> >> "numa-distance-map-v1" compatible device node.
> >>
> >> This fetches the NUMA node ID and distance map for these empty
> >> NUMA node from "numa-distance-map-v1" compatible device node.
> >
> > This is much nicer.
> >
>
> Indeed, thanks for your suggestions :)
>
> >> Signed-off-by: Gavin Shan <gshan@redhat.com>
> >> ---
> >>   drivers/of/of_numa.c | 2 ++
> >>   1 file changed, 2 insertions(+)
> >>
> >> diff --git a/drivers/of/of_numa.c b/drivers/of/of_numa.c
> >> index fe6b13608e51..5949829a1b00 100644
> >> --- a/drivers/of/of_numa.c
> >> +++ b/drivers/of/of_numa.c
> >> @@ -111,6 +111,8 @@ static int __init of_numa_parse_distance_map_v1(struct device_node *map)
> >>                          return -EINVAL;
> >>                  }
> >>
> >> +               node_set(nodea, numa_nodes_parsed);
> >> +
> >
> > With this, couldn't we remove of_numa_parse_cpu_nodes() as the only
> > thing it does is node_set()?
> >
>
> I don't think so for couple of reasons:
>
> (1) With problematic device-tree, the distance map node might be missed
>      or incomplete. In this case, of_numa_parse_cpu_nodes() still helps.

It's not the kernel's job to validate the DT (if it was, it is doing a
terrible job). I would suggest writing some checks for dtc if we're
worried about correctness. (The schemas don't work too well for cross
node checks.)

> (2) @numa_nodes_parsed is also updated when the memory nodes are iterated
>      in of_numa_parse_memory_nodes() and numa_add_memblk().
>
> So @numa_nodes_parsed, which is synchronized to @node_possible_map afterwards,
> is the gathering output of CPU nodes, memory nodes and distance map node.

Is it valid to have node id's that are not in the distance map?

Rob

  reply	other threads:[~2021-09-28 17:22 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27  6:41 [PATCH v2 0/2] Specify empty NUMA node Gavin Shan
2021-09-27  6:41 ` [PATCH v2 1/2] Documentation, dt, numa: Add note to " Gavin Shan
2021-10-04 18:13   ` Rob Herring
2021-09-27  6:41 ` [PATCH v2 2/2] of, numa: Fetch empty NUMA node ID from distance map Gavin Shan
2021-09-27 14:49   ` Rob Herring
2021-09-27 23:59     ` Gavin Shan
2021-09-28 17:22       ` Rob Herring [this message]
2021-09-29  2:00         ` Gavin Shan
2021-10-04 18:13   ` Rob Herring

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