On 01/27/2016 02:03 PM, Vlastimil Babka wrote: > 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.
Right. So indeed, static_key would be a good thing, but certainly an addon patch.
