| Message ID | 20240709023609.21332-1-richard.weiyang@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v5,1/3] mm/memblock: introduce a new helper memblock_estimated_nr_free_pages() | expand |
On Tue, Jul 09, 2024 at 02:36:07AM +0000, 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@gmail.com> > CC: David Hildenbrand <david@redhat.com> > Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Rapoport <rppt@kernel.org> > > --- > v5: cleanup the stale name > v4: adjust comment per david's suggestion > --- > include/linux/memblock.h | 1 + > mm/memblock.c | 17 +++++++++++++++++ > 2 files changed, 18 insertions(+) > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > index 40c62aca36ec..aba7ed9f2531 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_free_pages(void); > 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..ae8e58fc4e7f 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -1729,6 +1729,23 @@ 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. > + * > + * Return: > + * An estimated number of free pages from memblock point of view. > + */ > +unsigned long __init memblock_estimated_nr_free_pages(void) > +{ > + return PHYS_PFN(memblock_phys_mem_size() - memblock_reserved_size()); > +} > + > /* lowest address */ > phys_addr_t __init_memblock memblock_start_of_DRAM(void) > { > -- > 2.34.1 >
diff --git a/include/linux/memblock.h b/include/linux/memblock.h index 40c62aca36ec..aba7ed9f2531 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_free_pages(void); 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..ae8e58fc4e7f 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1729,6 +1729,23 @@ 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. + * + * Return: + * An estimated number of free pages from memblock point of view. + */ +unsigned long __init memblock_estimated_nr_free_pages(void) +{ + return PHYS_PFN(memblock_phys_mem_size() - memblock_reserved_size()); +} + /* lowest address */ phys_addr_t __init_memblock memblock_start_of_DRAM(void) {