linux-kernel - Re: [PATCH] mm: page_alloc: don't allocate page from memoryless nodes

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Message-ID: <a7f8be91-32c1-bfbe-7e81-5b1e818ba01d@redhat.com>
Date:   Tue, 14 Feb 2023 12:48:19 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Qi Zheng <zhengqi.arch@...edance.com>,
        Qi Zheng <arch0.zheng@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Teng Hu <huteng.ht@...edance.com>,
        Matthew Wilcox <willy@...radead.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Oscar Salvador <osalvador@...e.de>,
        Muchun Song <muchun.song@...ux.dev>
Subject: Re: [PATCH] mm: page_alloc: don't allocate page from memoryless nodes

On 14.02.23 12:44, Mike Rapoport wrote:
> (added x86 folks)
> 
> On Tue, Feb 14, 2023 at 12:29:42PM +0100, David Hildenbrand wrote:
>> On 14.02.23 12:26, Qi Zheng wrote:
>>> On 2023/2/14 19:22, David Hildenbrand wrote:
>>>>
>>>> TBH, this is the first time I hear of NODE_MIN_SIZE and it seems to be a
>>>> pretty x86 specific thing.
>>>>
>>>> Are we sure we want to get NODE_MIN_SIZE involved?
>>>
>>> Maybe add an arch_xxx() to handle it?
>>
>> I still haven't figured out what we want to achieve with NODE_MIN_SIZE at
>> all. It smells like an arch-specific hack looking at
>>
>> "Don't confuse VM with a node that doesn't have the minimum amount of
>> memory"
>>
>> Why shouldn't mm-core deal with that?
> 
> Well, a node with <4M RAM is not very useful and bears all the overhead of
> an extra live node.

And totally not with 4.1M, haha.

I really like the "Might fix boot" in the commit description.

> 
> But, hey, why won't we just drop that '< NODE_MIN_SIZE' and let people with
> weird HW configurations just live with this?


;)

-- 
Thanks,

David / dhildenb