From: David Hildenbrand <david@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>,
Mike Rapoport <rppt@kernel.org>, Michal Hocko <mhocko@kernel.org>,
Jia He <justin.he@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Baoquan He <bhe@redhat.com>, Chuhong Yuan <hslester96@gmail.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>,
linux-nvdimm <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 18:10:19 +0200 [thread overview]
Message-ID: <f80f2466-6e64-b525-dae1-66cb62ceb7f1@redhat.com> (raw)
In-Reply-To: <CAPcyv4guv2wjLDNJ4VN+4ZKiSC-FDvxoRxy5_OvUJ5C1tJsAGA@mail.gmail.com>
On 08.07.20 17:50, Dan Williams wrote:
> On Wed, Jul 8, 2020 at 3:04 AM David Hildenbrand <david@redhat.com> wrote:
>>
>> On 08.07.20 11:45, Mike Rapoport wrote:
>>> On Wed, Jul 08, 2020 at 11:25:36AM +0200, David Hildenbrand wrote:
>>>> On 08.07.20 11:15, Mike Rapoport wrote:
>>>>>>>>>>
>>>>>>> But on more theoretical/fundmanetal level, I think we lack a generic
>>>>>>> abstraction similar to e.g. x86 'struct numa_meminfo' that serves as
>>>>>>> translaton of firmware supplied information into data that can be used
>>>>>>> by the generic mm without need to reimplement it for each and every
>>>>>>> arch.
>>>>>>
>>>>>> Right. As I expressed, I am not a friend of using memblock for that, and
>>>>>> the pgdat node span is tricky.
>>>>>>
>>>>>> Maybe abstracting that x86 concept is possible in some way (and we could
>>>>>> restrict the information to boot-time properties, so we don't have to
>>>>>> mess with memory hot(un)plug - just as done for numa_meminfo AFAIKS).
>>>>>
>>>>> I agree with pgdat part and disagree about memblock. It already has
>>>>> non-init physmap, why won't we add memblock.memory to the mix? ;-)
>>>>
>>>> Can we generalize and tweak physmap to contain node info? That's all we
>>>> need, no? (the special mem= parameter handling should not matter for our
>>>> use case, where "physmap" and "memory" would differ)
>>>
>>> TBH, I have only random vague thoughts at the moment. This might be an
>>> option. But then we need to enable physmap on !s390, right?
>>
>> Yes, looks like it.
>>
>>>
>>>>> Now, seriously, memblock already has all the necessary information about
>>>>> the coldplug memory for several architectures. x86 being an exception
>>>>> because for some reason the reserved memory is not considered memory
>>>>> there. The infrastructure for quiering and iterating memory regions is
>>>>> already there. We just need to leave out the irrelevant parts, like
>>>>> memblock.reserved and allocation funcions.
>>>>
>>>> I *really* don't want to mess with memblocks on memory hot(un)plug on
>>>> x86 and s390x (+other architectures in the future). I also thought about
>>>> stopping to create memblocks for hotplugged memory on arm64, by tweaking
>>>> pfn_valid() to query memblocks only for early sections.
>>>>
>>>> If "physmem" is not an option, can we at least introduce something like
>>>> ARCH_UPDTAE_MEMBLOCK_ON_HOTPLUG to avoid doing that on x86 and s390x for
>>>> now (and later maybe for others)?
>>>
>>> I have to do more memory hotplug howework to answer that ;-)
>>>
>>> My general point is that we don't have to reinvent the wheel to have
>>> coldplug memory representation, it's already there. We just need a way
>>> to use it properly.
>>
>> Yes, I tend to agree. Details to be clarified :)
>
> I'm not quite understanding the concern, or requirement about
> "updating memblock" in the hotplug path. The routines
> memory_add_physaddr_to_nid() and phys_to_target_node() are helpers to
> interrogate platform-firmware numa info through a common abstraction.
> They place no burden on the memory hotplug code they're just used to
> see if a hot-added range lies within an existing node span when
> platform-firmware otherwise fails to communicate a node. x86 can
> continue to back those helpers with numa_meminfo, arm64 can use a
> generic memblock implementation and other archs can follow the arm64
> example if they want better numa answers for drivers.
>
See memblock_add_node()/memblock_remove() in mm/memory_hotplug.c. I
don't want that code be reactivated for x86/s390x. That's all I am saying.
--
Thanks,
David / dhildenb
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
next prev parent reply other threads:[~2020-07-08 16:10 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=f80f2466-6e64-b525-dae1-66cb62ceb7f1@redhat.com \
--to=david@redhat.com \
--cc=Kaly.Xin@arm.com \
--cc=akpm@linux-foundation.org \
--cc=bhe@redhat.com \
--cc=catalin.marinas@arm.com \
--cc=dan.j.williams@intel.com \
--cc=hslester96@gmail.com \
--cc=justin.he@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-nvdimm@lists.01.org \
--cc=mhocko@kernel.org \
--cc=rppt@kernel.org \
--cc=rppt@linux.ibm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).