lkml.org 
[lkml]   [2022]   [May]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v10 2/4] mm: memory_hotplug: override memmap_on_memory when hugetlb_free_vmemmap=on
From
On 12.05.22 14:50, Muchun Song wrote:
> On Thu, May 12, 2022 at 09:36:15AM +0200, David Hildenbrand wrote:
>> On 09.05.22 08:27, Muchun Song wrote:
>>> Optimizing HugeTLB vmemmap pages is not compatible with allocating memmap on
>>> hot added memory. If "hugetlb_free_vmemmap=on" and
>>> memory_hotplug.memmap_on_memory" are both passed on the kernel command line,
>>> optimizing hugetlb pages takes precedence.
>>
>> Why?
>>
>
> Because both two features are not compatible since hugetlb_free_vmemmap cannot
> optimize the vmemmap pages allocated from alternative allocator (when
> memory_hotplug.memmap_on_memory=1). So when the feature of hugetlb_free_vmemmap
> is introduced, I made hugetlb_free_vmemmap take precedence. BTW, I have a plan
> to remove this restriction, I'll post it out ASAP.

I was asking why vmemmap optimization should take precedence.
memmap_on_memory makes it more likely to succeed memory hotplug in
close-to-OOM situations -- which is IMHO more important than a vmemmap
optimization.

But anyhow, the proper approach should most probably be to simply not
mess with the vmemmap if we stumble over a vmemmap that's special due to
memmap_on_memory. I assume that's what you're talking about sending out.

--
Thanks,

David / dhildenb

\
 
 \ /
  Last update: 2022-05-12 15:06    [W:3.200 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site