On 12.04.20 21:48, Mike Rapoport wrote:
> From: Baoquan He <bhe@xxxxxxxxxx>
>
> 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 <bhe@xxxxxxxxxx>
> Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> ---
> 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
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