From: Mike Rapoport <rppt@linux.ibm.com>
To: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
Justin He <Justin.He@arm.com>, Michal Hocko <mhocko@kernel.org>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <will@kernel.org>,
Vishal Verma <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Baoquan He <bhe@redhat.com>, Chuhong Yuan <hslester96@gmail.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Kaly Xin <Kaly.Xin@arm.com>
Subject: Re: [PATCH v2 1/3] arm64/numa: export memory_add_physaddr_to_nid as EXPORT_SYMBOL_GPL
Date: Wed, 8 Jul 2020 10:43:25 +0300 [thread overview]
Message-ID: <20200708074325.GG386073@linux.ibm.com> (raw)
In-Reply-To: <6aae78fa-b505-0f76-087b-d8b2146c62f1@redhat.com>
On Wed, Jul 08, 2020 at 09:16:01AM +0200, David Hildenbrand wrote:
> On 08.07.20 09:04, Dan Williams wrote:
> > On Tue, Jul 7, 2020 at 11:59 PM David Hildenbrand <david@redhat.com> wrote:
> >>
> >> On 08.07.20 08:22, Mike Rapoport wrote:
> >>> On Tue, Jul 07, 2020 at 09:27:43PM -0700, Dan Williams wrote:
> >>>> On Tue, Jul 7, 2020 at 9:08 PM Justin He <Justin.He@arm.com> wrote:
> >>>> [..]
> >>>>>> Especially for architectures that use memblock info for numa info
> >>>>>> (which seems to be everyone except x86) why not implement a generic
> >>>>>> memory_add_physaddr_to_nid() that does:
> >>>>>>
> >>>>>> int memory_add_physaddr_to_nid(u64 addr)
> >>>>>> {
> >>>>>> unsigned long start_pfn, end_pfn, pfn = PHYS_PFN(addr);
> >>>>>> int nid;
> >>>>>>
> >>>>>> for_each_online_node(nid) {
> >>>>>> get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
> >>>>>> if (pfn >= start_pfn && pfn <= end_pfn)
> >>>>>> return nid;
> >>>>>> }
> >>>>>> return NUMA_NO_NODE;
> >>>>>> }
> >>>>>
> >>>>> Thanks for your suggestion,
> >>>>> Could I wrap the codes and let memory_add_physaddr_to_nid simply invoke
> >>>>> phys_to_target_node()?
> >>>>
> >>>> I think it needs to be the reverse. phys_to_target_node() should call
> >>>> memory_add_physaddr_to_nid() by default, but fall back to searching
> >>>> reserved memory address ranges in memblock. See phys_to_target_node()
> >>>> in arch/x86/mm/numa.c. That one uses numa_meminfo instead of memblock,
> >>>> but the principle is the same i.e. that a target node may not be
> >>>> represented in memblock.memory, but memblock.reserved. I'm working on
> >>>> a patch to provide a function similar to get_pfn_range_for_nid() that
> >>>> operates on reserved memory.
> >>>
> >>> Do we really need yet another memblock iterator?
> >>> I think only x86 has memory that is not in memblock.memory but only in
> >>> memblock.reserved.
> >>
> >> Reading about abusing the memblock allcoator once again in memory
> >> hotplug paths makes me shiver.
> >
> > Technical reasoning please?
>
> ARCH_KEEP_MEMBLOCK is (AFAIK) only a hack for arm64 to implement
> pfn_valid(), because they zap out individual pages corresponding to
> memory holes of full sections.
>
> I am not a friend of adding more post-init code to rely on memblock
> data. It just makes it harder to eventually get rid of ARCH_KEEP_MEMBLOCK.
The most heavy user of memblock in post-init code is powerpc. It won't
be easy to get rid of it there.
> > arm64 numa information is established from memblock data. It seems
> > counterproductive to ignore that fact if we're already touching
> > memory_add_physaddr_to_nid() and have a use case for a driver to call
> > it.
>
> ... and we are trying to handle the "only a single dummy node" case
> (patch #2), or what am I missing? What is there to optimize currently?
>
> --
> Thanks,
>
> David / dhildenb
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2020-07-08 7:43 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-07 5:59 [PATCH v2 0/3] Fix and enable pmem as RAM device on arm64 Jia He
2020-07-07 5:59 ` [PATCH v2 1/3] arm64/numa: export memory_add_physaddr_to_nid as EXPORT_SYMBOL_GPL Jia He
2020-07-07 11:35 ` David Hildenbrand
2020-07-07 11:54 ` Michal Hocko
2020-07-07 12:13 ` Mike Rapoport
2020-07-07 12:26 ` David Hildenbrand
2020-07-07 18:00 ` Mike Rapoport
2020-07-07 22:05 ` Dan Williams
2020-07-08 5:27 ` Mike Rapoport
2020-07-08 7:21 ` David Hildenbrand
2020-07-08 7:38 ` Mike Rapoport
2020-07-08 7:40 ` David Hildenbrand
2020-07-08 7:50 ` Dan Williams
2020-07-08 8:26 ` David Hildenbrand
2020-07-08 8:39 ` Mike Rapoport
2020-07-08 8:45 ` David Hildenbrand
2020-07-08 9:15 ` Mike Rapoport
2020-07-08 9:25 ` David Hildenbrand
2020-07-08 9:45 ` Mike Rapoport
2020-07-08 10:04 ` David Hildenbrand
2020-07-08 15:50 ` Dan Williams
2020-07-08 16:10 ` David Hildenbrand
2020-07-08 16:47 ` Mike Rapoport
2020-07-08 2:20 ` Justin He
2020-07-08 3:56 ` Dan Williams
2020-07-08 4:08 ` Justin He
2020-07-08 4:27 ` Dan Williams
2020-07-08 6:22 ` Mike Rapoport
2020-07-08 6:53 ` Dan Williams
2020-07-08 6:59 ` David Hildenbrand
2020-07-08 7:04 ` Dan Williams
2020-07-08 7:16 ` David Hildenbrand
2020-07-08 7:43 ` Mike Rapoport [this message]
2020-07-08 5:32 ` Mike Rapoport
2020-07-08 5:48 ` Dan Williams
2020-07-08 6:19 ` Mike Rapoport
2020-07-08 6:44 ` Dan Williams
2020-07-08 6:56 ` Justin He
2020-07-08 7:00 ` David Hildenbrand
2020-07-07 5:59 ` [RFC PATCH v2 2/3] device-dax: use fallback nid when numa_node is invalid Jia He
2020-07-07 6:08 ` Justin He
2020-07-07 11:34 ` David Hildenbrand
2020-07-08 1:41 ` Justin He
2020-07-07 5:59 ` [PATCH v2 3/3] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done Jia He
2020-07-07 10:06 ` Michal Hocko
2020-07-07 11:31 ` David Hildenbrand
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