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mm: sparse: pass section_nr to find_memory_block

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With CONFIG_SPARSEMEM_EXTREME enabled, __section_nr() which converts
mem_section to section_nr could be costly since it iterates all section
roots to check if the given mem_section is in its range.

On the other hand, __nr_to_section() which converts section_nr to
mem_section can be done in O(1).

Let's pass section_nr instead of mem_section ptr to find_memory_block() in
order to reduce needless iterations.

Link: https://lkml.kernel.org/r/20210707150212.855-3-ohoono.kwon@samsung.com
Signed-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ohhoon Kwon 2021-09-02 14:57:01 -07:00 committed by Linus Torvalds
parent a1bc561bb2
commit fc1f5e980a
3 changed files with 4 additions and 6 deletions
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4
arch/powerpc/platforms/pseries/hotplug-memory.c
View File

@ -211,13 +211,11 @@ static int update_lmb_associativity_index(struct drmem_lmb *lmb)
static struct memory_block *lmb_to_memblock(struct drmem_lmb *lmb)
{
unsigned long section_nr;
struct mem_section *mem_sect;
struct memory_block *mem_block;
section_nr = pfn_to_section_nr(PFN_DOWN(lmb->base_addr));
mem_sect = __nr_to_section(section_nr);
mem_block = find_memory_block(mem_sect);
mem_block = find_memory_block(section_nr);
return mem_block;
}

4
drivers/base/memory.c
View File

@ -578,9 +578,9 @@ static struct memory_block *find_memory_block_by_id(unsigned long block_id)
/*
* Called under device_hotplug_lock.
*/
struct memory_block *find_memory_block(struct mem_section *section)
struct memory_block *find_memory_block(unsigned long section_nr)
{
unsigned long block_id = memory_block_id(__section_nr(section));
unsigned long block_id = memory_block_id(section_nr);
return find_memory_block_by_id(block_id);
}

2
include/linux/memory.h
View File

@ -90,7 +90,7 @@ int create_memory_block_devices(unsigned long start, unsigned long size,
void remove_memory_block_devices(unsigned long start, unsigned long size);
extern void memory_dev_init(void);
extern int memory_notify(unsigned long val, void *v);
extern struct memory_block *find_memory_block(struct mem_section *);
extern struct memory_block *find_memory_block(unsigned long section_nr);
typedef int (*walk_memory_blocks_func_t)(struct memory_block *, void *);
extern int walk_memory_blocks(unsigned long start, unsigned long size,
void *arg, walk_memory_blocks_func_t func);