From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: akpm@linux-foundation.org, dan.j.williams@intel.com,
pasha.tatashin@soleen.com, mhocko@suse.com,
anshuman.khandual@arm.com, Jonathan.Cameron@huawei.com,
vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/5] mm,memory_hotplug: Introduce MHP_MEMMAP_ON_MEMORY
Date: Fri, 26 Jul 2019 11:37:07 +0200 [thread overview]
Message-ID: <bcb326c5-7a68-86de-ca92-1d41cfcb9bfd@redhat.com> (raw)
In-Reply-To: <20190726092959.GB26268@linux>
>>
>>>
>>> or
>>> add_memory(0x1000, size_memory_block * 3);
>>>
>>> [memblock #0 ]
>>> [0 - 1533 pfns ] - vmemmap for section#{0-2}
>>> [1534 - 98304 pfns] - normal memory
>>>
>>> When using larger memory blocks (1GB or 2GB), the principle is the same.
>>>
>>> Of course, per whole-range granularity is nicer when it comes to have a large
>>> contigous area, while per memory-block granularity allows us to have flexibility
>>> when removing the memory.
>>
>> E.g., in my virtio-mem I am currently adding all memory blocks
>> separately either way (to guranatee that remove_memory() works cleanly -
>> see __release_memory_resource()), and to control the amount of
>> not-offlined memory blocks (e.g., to make user space is actually
>> onlining them). As it's just a prototype, this might change of course in
>> the future.
>
> What is virtio-mem for? Did it that raised from a need?
> Is it something you could try this patch on?
virtio-mem is a paravirtualized way of hotplugging/removing to/from a
guest. (similar to, but different to e.g., the hv-balloon). It
adds/removes memory to/from the system. In the long term, it will try to
also act similar-but different to a balloon - but that will require more
work. In the first shot, it's all about adding/removing memory in the
smaller granularity possible.
The old prototype was
https://lwn.net/Articles/755423/
Since then, a lot changed. Some more updated information is at
https://events.linuxfoundation.org/wp-content/uploads/2017/12/virtio-mem-Paravirtualized-Memory-David-Hildenbrand-Red-Hat-1.pdf
There is also a recording of the presentation on youtube.
The current prototype is unfortunately not in a state yet that allows me
to test with this patch set - my Master's thesis consumed most of my
energy during the last year. I just started hacking on it again.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2019-07-26 9:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 16:02 [PATCH v3 0/5] Allocate memmap from hotadded memory Oscar Salvador
2019-07-25 16:02 ` [PATCH v3 1/5] mm,memory_hotplug: Introduce MHP_MEMMAP_ON_MEMORY Oscar Salvador
2019-07-26 8:34 ` David Hildenbrand
2019-07-26 9:29 ` Oscar Salvador
2019-07-26 9:37 ` David Hildenbrand [this message]
2019-07-25 16:02 ` [PATCH v3 2/5] mm: Introduce a new Vmemmap page-type Oscar Salvador
2019-07-26 8:48 ` David Hildenbrand
2019-07-26 9:25 ` Oscar Salvador
2019-07-26 9:41 ` David Hildenbrand
2019-07-26 10:11 ` Oscar Salvador
2019-07-25 16:02 ` [PATCH v3 3/5] mm,sparse: Add SECTION_USE_VMEMMAP flag Oscar Salvador
2019-08-01 14:45 ` David Hildenbrand
2019-07-25 16:02 ` [PATCH v3 4/5] mm,memory_hotplug: Allocate memmap from the added memory range for sparse-vmemmap Oscar Salvador
2019-08-01 15:04 ` David Hildenbrand
2019-07-25 16:02 ` [PATCH v3 5/5] mm,memory_hotplug: Allow userspace to enable/disable vmemmap Oscar Salvador
2019-08-01 15:07 ` David Hildenbrand
2019-07-25 16:56 ` [PATCH v3 0/5] Allocate memmap from hotadded memory David Hildenbrand
2019-08-01 7:39 ` Oscar Salvador
2019-08-01 8:17 ` David Hildenbrand
2019-08-01 8:39 ` Oscar Salvador
2019-08-01 8:44 ` David Hildenbrand
2019-08-01 18:46 ` David Hildenbrand
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