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

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Date:   Tue, 14 Feb 2023 14:46:17 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     David Hildenbrand <david@...hat.com>
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>, x86@...nel.org
Subject: Re: [PATCH] mm: page_alloc: don't allocate page from memoryless nodes

Now added x86 folks for real :)

The thread starts here:
https://lore.kernel.org/all/20230212110305.93670-1-zhengqi.arch@bytedance.com/

On Tue, Feb 14, 2023 at 01:44:06PM +0200, 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.
> 
> But, hey, why won't we just drop that '< NODE_MIN_SIZE' and let people with
> weird HW configurations just live with this?
>  
> > I'd appreciate an explanation of the bigger picture, what the issue is and
> > what the approach to solve it is (including memory onlining/offlining).
> > 
> > -- 
> > Thanks,
> > 
> > David / dhildenb
> > 
> 
> -- 
> Sincerely yours,
> Mike.
> 

-- 
Sincerely yours,
Mike.