Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting

[Vlastimil Babka]

On 01/27/2016 01:47 PM, Christian Borntraeger wrote:
> On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
>> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
>> 
>> I think it might be worth also to convert debug_pagealloc_enabled() to be based
>> on static key, like I did for page_owner [1]. That should help make it possible
>> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
>> without enabling it boot-time. I assume it's one of the goals here?
> 
> We could do something like that but dump_stack and setup of the initial identity
> mapping of the kernel as well as the initial page protection are not hot path
> as far as I can tell. Any other places?

Well, mostly kernel_map_pages() which is used in page allocation hotpaths.

>> 
>> [1] http://www.spinics.net/lists/linux-mm/msg100795.html
> 
> 
> 
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