From: David Hildenbrand <david@redhat.com>
To: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: linux-mm@kvack.org, Arjan van de Ven <arjan@linux.intel.com>,
Feng Tang <feng.tang@intel.com>
Subject: Re: Deferred Memory Init: How to bring rest of memory online after limiting it with `mem=XG`?
Date: Thu, 3 Dec 2020 14:06:05 +0100 [thread overview]
Message-ID: <7692e410-886e-a1bb-4158-e02305fcd013@redhat.com> (raw)
In-Reply-To: <8a395c1a-764b-9d82-0a12-b1a9254f8d53@molgen.mpg.de>
On 03.12.20 13:52, Paul Menzel wrote:
> Dear David,
>
>
> Thank you for the quick response.
>
>
> Am 03.12.20 um 13:25 schrieb David Hildenbrand:
>> On 03.12.20 11:51, Paul Menzel wrote:
>
>>> I am trying to reduce the startup time of Debian’s Linux 5.9.9 on a
>>> Intel Kaby Lake system with 32 GB of memory (TUXEDO Book BU1406 (Clevo
>>> N240BU)).
>
> […]
>
>> We do have deferred meminit in the kernel during boot that can
>> initialize memory in parallel.
>
> Is that used automatically, or do I need to activate it somehow?
If your kernel is compiled with
CONFIG_DEFERRED_STRUCT_PAGE_INIT
it should be enabled automatically.
config DEFERRED_STRUCT_PAGE_INIT
bool "Defer initialisation of struct pages to kthreads"
depends on SPARSEMEM
depends on !NEED_PER_CPU_KM
depends on 64BIT
select PADATA
help
Ordinarily all struct pages are initialised during early boot in a
single thread. On very large machines this can take a considerable
amount of time. If this option is set, large machines will bring up
a subset of memmap at boot and then initialise the rest in parallel.
This has a potential performance impact on tasks running early in the
lifetime of the system until these kthreads finish the
initialisation.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-12-03 13:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 10:51 Paul Menzel
2020-12-03 12:25 ` David Hildenbrand
2020-12-03 12:52 ` Paul Menzel
2020-12-03 13:06 ` David Hildenbrand [this message]
2020-12-03 20:58 ` Daniel Jordan
2020-12-04 7:31 ` Paul Menzel
2020-12-04 19:50 ` Daniel Jordan
2020-12-04 1:17 ` Feng Tang
2020-12-04 8:05 ` Feng Tang
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