From: David Hildenbrand <david@redhat.com>
To: "Ranjan, Vikash" <Vikash.Ranjan@harman.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: memory_block_size reduction in memory hot plug, can we reduced it to 1GB,currently it is 4GB
Date: Sun, 9 Jan 2022 13:25:46 +0100 [thread overview]
Message-ID: <4821e34b-b7b5-a281-588d-fe8242856b6b@redhat.com> (raw)
In-Reply-To: <14101f99fda548dc960e2041a6807536@HIBDWSMB03.ad.harman.com>
Hi
>
> We are trying to enable memory hot plug for our device's based on arm64,
> is it possible to reduce memory_block_size to 1 GB or lesser as
> currently it is 4GB.
... are you sure it's 4GB? I never heard that magic number on arm64
before. The section size is 512 MiB on arm64 with 64k and 128 MiB with 4k.
>
> If you have any info on updated patch or any other way we can do this,
> please let us know.
>
> After applying attached test patch (for reduction of memory_block_size
> to 1 GB),we are getting below error. Probe is working fine in case of 4GB.
>
I think I am missing something important.
#define MIN_MEMORY_BLOCK_SIZE (1UL << SECTION_SIZE_BITS)
arch/arm64/include/asm/sparsemem.h:#define SECTION_SIZE_BITS 29
arch/arm64/include/asm/sparsemem.h:#define SECTION_SIZE_BITS 27
-> 512 MiB / 128 MiB
arm64 does not override memory_block_size_bytes(), so it matches exactly
these numbers.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2022-01-09 12:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-06 7:04 Ranjan, Vikash
2022-01-09 12:25 ` David Hildenbrand [this message]
2022-01-10 16:07 ` [EXTERNAL] Re: memory_block_size reduction in memory hot plug, can we reduced it to 1GB, currently " Ranjan, Vikash
2022-01-10 16:22 ` David Hildenbrand
2022-01-11 3:53 ` Ranjan, Vikash
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