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From: Michal Hocko <mhocko@kernel.org>
To: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>,
	akpm@linux-foundation.org, dan.j.williams@intel.com,
	Jonathan.Cameron@huawei.com, anshuman.khandual@arm.com,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 0/4] mm,memory_hotplug: allocate memmap from hotadded memory
Date: Wed, 3 Apr 2019 12:46:02 +0200	[thread overview]
Message-ID: <20190403104602.GJ15605@dhcp22.suse.cz> (raw)
In-Reply-To: <20190403094054.jdr7lxm45htgcsk7@d104.suse.de>

On Wed 03-04-19 11:40:54, Oscar Salvador wrote:
> On Wed, Apr 03, 2019 at 10:37:57AM +0200, Michal Hocko wrote:
> > That being said it should be the caller of the hotplug code to tell
> > the vmemmap allocation strategy. For starter, I would only pack vmemmaps
> > for "regular" kernel zone memory. Movable zones should be more careful.
> > We can always re-evaluate later when there is a strong demand for huge
> > pages on movable zones but this is not the case now because those pages
> > are not really movable in practice.
> 
> I agree that makes sense to let the caller specify if it wants to allocate
> vmemmaps per memblock or per memory-range, so we are more flexible when it
> comes to granularity in hot-add/hot-remove operations.

And just to be more specific. The api shouldn't really care about this
implementation detail. So ideally the caller of add_pages just picks up
the proper allocator and the rest is completely transparent.

> But the thing is that the zones are picked at onling stage, while
> vmemmaps are created at hot-add stage, so I am not sure we can define
> the strategy depending on the zone.

THis is a good point. We do have means to tell a default zone for the
regular memory hotplug so this can be reused based on the pfn range
(default_zone_for_pfn).
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2019-04-03 10:46 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-28 13:43 [PATCH 0/4] mm,memory_hotplug: allocate memmap from hotadded memory Oscar Salvador
2019-03-28 13:43 ` [PATCH 1/4] mm, memory_hotplug: cleanup memory offline path Oscar Salvador
2019-04-03  8:43   ` Michal Hocko
2019-03-28 13:43 ` [PATCH 2/4] mm, memory_hotplug: provide a more generic restrictions for memory hotplug Oscar Salvador
2019-04-03  8:46   ` Michal Hocko
2019-04-03  8:48     ` David Hildenbrand
2019-04-04 10:04     ` Oscar Salvador
2019-04-04 10:06       ` David Hildenbrand
2019-04-04 10:31       ` Michal Hocko
2019-04-04 12:04         ` Oscar Salvador
2019-03-28 13:43 ` [PATCH 3/4] mm, memory_hotplug: allocate memmap from the added memory range for sparse-vmemmap Oscar Salvador
2019-03-28 13:43 ` [PATCH 4/4] mm, sparse: rename kmalloc_section_memmap, __kfree_section_memmap Oscar Salvador
2019-03-28 15:09 ` [PATCH 0/4] mm,memory_hotplug: allocate memmap from hotadded memory David Hildenbrand
2019-03-28 15:31   ` David Hildenbrand
2019-03-29  8:45     ` Oscar Salvador
2019-03-29  8:56       ` David Hildenbrand
2019-03-29  9:01         ` David Hildenbrand
2019-03-29  9:20         ` Oscar Salvador
2019-03-29 13:42       ` Michal Hocko
2019-04-01  7:59         ` Oscar Salvador
2019-04-01 11:53           ` Michal Hocko
2019-04-02  8:28             ` Oscar Salvador
2019-04-02  8:39               ` David Hildenbrand
2019-04-02 12:48               ` Michal Hocko
2019-04-03  8:01                 ` Oscar Salvador
2019-04-03  8:12                   ` Michal Hocko
2019-04-03  8:17                     ` David Hildenbrand
2019-04-03  8:37                       ` Michal Hocko
2019-04-03  8:41                         ` David Hildenbrand
2019-04-03  8:49                           ` Michal Hocko
2019-04-03  8:53                             ` David Hildenbrand
2019-04-03  8:50                           ` Oscar Salvador
2019-04-03  8:54                             ` David Hildenbrand
2019-04-03  9:40                         ` Oscar Salvador
2019-04-03 10:46                           ` Michal Hocko [this message]
2019-04-04 10:25                           ` Vlastimil Babka
2019-04-03  8:34                     ` Oscar Salvador
2019-04-03  8:36                       ` David Hildenbrand
2019-03-29  8:30   ` Oscar Salvador
2019-03-29  8:51     ` David Hildenbrand
2019-03-29 22:23 ` John Hubbard
2019-04-01  7:52   ` Oscar Salvador

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