From: Daniel Jordan <daniel.m.jordan@oracle.com>
To: David Hildenbrand <david@redhat.com>,
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, 03 Dec 2020 15:58:19 -0500 [thread overview]
Message-ID: <87v9disj2s.fsf@oracle.com> (raw)
In-Reply-To: <7692e410-886e-a1bb-4158-e02305fcd013@redhat.com>
David Hildenbrand <david@redhat.com> writes:
> 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.
Hello Paul,
If it is enabled, what does
dmesg | grep 'deferred pages'
give you? And assuming you're running systemd, what does
systemd-analyze show you?
Thanks.
next prev parent reply other threads:[~2020-12-03 20:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 10:51 Deferred Memory Init: How to bring rest of memory online after limiting it with `mem=XG`? Paul Menzel
2020-12-03 12:25 ` David Hildenbrand
2020-12-03 12:52 ` Paul Menzel
2020-12-03 13:06 ` David Hildenbrand
2020-12-03 20:58 ` Daniel Jordan [this message]
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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