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Subject: Re: [PATCH v2 1/3] mm: vmalloc: Let user to control huge vmalloc
 default behavior
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To:     Matthew Wilcox <willy@infradead.org>
CC:     Nicholas Piggin <npiggin@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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From:   Kefeng Wang <wangkefeng.wang@huawei.com>
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On 2022/1/19 21:22, Matthew Wilcox wrote:
> On Wed, Jan 19, 2022 at 08:57:58PM +0800, Kefeng Wang wrote:
>> Only parts of our products wants this feature,  we add some interfaces which
>> only
>>
>> alloc hugevmalloc for them, eg,
>> vmap_hugepage/vmalloc_hugepage/remap_vmalloc_hugepage_range..
>>
>> for our products, but it's not the choice of most products, also add
>> nohugevmalloc
>>
>> for most products is expensive, so this is the reason for adding the patch.
>>
>> more config/cmdline are more flexible for test/products，
> But why do only some products want it?  What goes wrong if all products
> enable it?  Features should be auto-tuning, not relying on admins to
> understand them.

Because this feature will use more memory for vmalloc/vmap, that's why 
we add some explicit
interfaces as said above in our kernel to control the user.