Re: [PATCH 15/21] mm: memmap_init: iterate over memblock regions rather that check each PFN
From: David Hildenbrand <hidden>
Date: 2020-04-24 07:23:08
Also in:
linux-alpha, linux-arch, linux-mm, linux-riscv, linux-um
On 12.04.20 21:48, Mike Rapoport wrote:
quoted hunk ↗ jump to hunk
From: Baoquan He <redacted> When called during boot the memmap_init_zone() function checks if each PFN is valid and actually belongs to the node being initialized using early_pfn_valid() and early_pfn_in_nid(). Each such check may cost up to O(log(n)) where n is the number of memory banks, so for large amount of memory overall time spent in early_pfn*() becomes substantial. Since the information is anyway present in memblock, we can iterate over memblock memory regions in memmap_init() and only call memmap_init_zone() for PFN ranges that are know to be valid and in the appropriate node. Signed-off-by: Baoquan He <redacted> Signed-off-by: Mike Rapoport <redacted> --- mm/page_alloc.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-)diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7f6a3081edb8..c43ce8709457 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c@@ -5995,14 +5995,6 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, * function. They do not exist on hotplugged memory. */
After this change, the comment above is stale. the "holes in boot-time mem_map" are handled by the caller now AFAIKs.
if (context == MEMMAP_EARLY) {
- if (!early_pfn_valid(pfn)) {
- pfn = next_pfn(pfn);
- continue;
- }
- if (!early_pfn_in_nid(pfn, nid)) {
- pfn++;
- continue;
- }
if (overlap_memmap_init(zone, &pfn))
continue;
if (defer_init(nid, pfn, end_pfn))-- Thanks, David / dhildenb