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From: David Hildenbrand <david@redhat.com>
To: Huang Shijie <shijie@os.amperecomputing.com>
Cc: viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
	jlayton@kernel.org, bfields@fieldses.org,
	torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	song.bao.hua@hisilicon.com, patches@amperecomputing.com,
	zwang@amperecomputing.com
Subject: Re: [RFC PATCH] fs/exec: Add the support for ELF program's NUMA replication
Date: Thu, 9 Sep 2021 10:58:49 +0200	[thread overview]
Message-ID: <1c115101-a549-0e88-7bbb-1b0a19621504@redhat.com> (raw)
In-Reply-To: <YTnX7IyC420MNBLq@hsj>

On 09.09.21 11:46, Huang Shijie wrote:
> On Mon, Sep 06, 2021 at 11:35:01AM +0200, David Hildenbrand wrote:
>> On 06.09.21 18:16, Huang Shijie wrote:
>>> This patch adds AT_NUMA_REPLICATION for execveat().
>>>
>>> If this flag is set, the kernel will trigger COW(copy on write)
>>> on the mmapped ELF binary. So the program will have a copied-page
>>> on its NUMA node, even if the original page in page cache is
>>> on other NUMA nodes.
>>
>> Am I missing something important or is this just absolutely not what we
>> want?
> 
> Please see the thread:
> https://marc.info/?l=linux-kernel&m=163070220429222&w=2
> 
> Linus did not think it is a good choice to implement the "per-numa node page cache"

That doesn't make this approach any better.

I don't think we want this in the kernel. If user space wants to waste 
memory, it can happily mmap() however it wants. The advisory is to not 
do it.

-- 
Thanks,

David / dhildenb


  reply	other threads:[~2021-09-09  8:58 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-06 16:16 [RFC PATCH] fs/exec: Add the support for ELF program's NUMA replication Huang Shijie
2021-09-06  9:35 ` David Hildenbrand
2021-09-09  9:46   ` Huang Shijie
2021-09-09  8:58     ` David Hildenbrand [this message]
2021-09-06 12:09 ` Matthew Wilcox
2021-09-09  9:48   ` Huang Shijie
2021-09-09  1:43 ` kernel test robot

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