!3044 mm: hugetlb: Skip initialization of gigantic tail struct pages if freed by HVO

Merge Pull Request from: @ci-robot 
 
PR sync from: Jinjiang Tu <tujinjiang@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/SEQFWVLMJCSUOJXMC3CRL6DQ62SBEZFG/ 
This series moves the boot time initialization of tail struct pages of a
gigantic page to later on in the boot. Only the
HUGETLB_VMEMMAP_RESERVE_SIZE / sizeof(struct page) - 1 tail struct pages
are initialized at the start. If HVO is successful, then no more tail struct
pages need to be initialized. For a 1G hugepage, this series avoid
initialization of 262144 - 63 = 262081 struct pages per hugepage.

When tested on a 512G system (allocating 500 1G hugepages), the
kexec-boot times with DEFERRED_STRUCT_PAGE_INIT enabled are:

- with patches, HVO enabled: 1.32 seconds
- with patches, HVO disabled: 2.15 seconds
- without patches, HVO enabled: 3.90  seconds
- without patches, HVO disabled: 3.58 seconds

This represents an approximately 70% reduction in boot time and will
significantly reduce server downtime when using a large number of
gigantic pages.

Usama Arif (4):
  mm: hugetlb_vmemmap: use nid of the head page to reallocate it
  memblock: pass memblock_type to memblock_setclr_flag
  memblock: introduce MEMBLOCK_RSRV_NOINIT flag
  mm: hugetlb: skip initialization of gigantic tail struct pages if
    freed by HVO


-- 
2.25.1
 
https://gitee.com/openeuler/kernel/issues/I8JXRC 
 
Link:https://gitee.com/openeuler/kernel/pulls/3044

 

Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>