On Mon, Jul 08, 2024 at 09:56:21AM +0200, David Hildenbrand wrote: >On 08.07.24 03:00, Wei Yang wrote: >> During bootup, system may need the number of free pages in the whole system >> to do some calculation before all pages are freed to buddy system. Usually >> this number is get from totalram_pages(). Since we plan to move the free >> pages accounting in __free_pages_core(), this value may not represent >> total free pages at the early stage, especially when >> CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled. >> >> Instead of using raw memblock api, let's introduce a new helper for user >> to get the estimated number of free pages from memblock point of view. >> >> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx> >> CC: David Hildenbrand <david@xxxxxxxxxx> >> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> >> >> --- >> v4: adjust comment per david's suggestion >> --- >> include/linux/memblock.h | 1 + >> mm/memblock.c | 20 ++++++++++++++++++++ >> 2 files changed, 21 insertions(+) >> >> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >> index 40c62aca36ec..7d1c32b3dc12 100644 >> --- a/include/linux/memblock.h >> +++ b/include/linux/memblock.h >> @@ -486,6 +486,7 @@ static inline __init_memblock bool memblock_bottom_up(void) >> phys_addr_t memblock_phys_mem_size(void); >> phys_addr_t memblock_reserved_size(void); >> +unsigned long memblock_estimated_nr_pages(void); > >^ stale name My bad. > >> phys_addr_t memblock_start_of_DRAM(void); >> phys_addr_t memblock_end_of_DRAM(void); >> void memblock_enforce_memory_limit(phys_addr_t memory_limit); >> diff --git a/mm/memblock.c b/mm/memblock.c >> index e81fb68f7f88..26162902789f 100644 >> --- a/mm/memblock.c >> +++ b/mm/memblock.c >> @@ -1729,6 +1729,26 @@ phys_addr_t __init_memblock memblock_reserved_size(void) >> return memblock.reserved.total_size; >> } >> +/** >> + * memblock_estimated_nr_free_pages - return estimated number of free pages >> + * from memblock point of view >> + * >> + * During bootup, subsystems might need a rough estimate of the number of free >> + * pages in the whole system, before precise numbers are available from the >> + * buddy. Especially with CONFIG_DEFERRED_STRUCT_PAGE_INIT, the numbers >> + * obtained from the buddy might be very imprecise during bootup. >> + * >> + * While we can get the estimated number of free pages from memblock, which is >> + * good enough for estimation. > >I'd drop that sentence. > Will update it. > >Apart form that LGTM > >-- >Cheers, > >David / dhildenb -- Wei Yang Help you, Help me
