On 07/10/2018 11:49 AM, Cannon Matthews wrote: > When using 1GiB pages during early boot, use the new > memblock_virt_alloc_try_nid_raw() function to allocate memory without > zeroing it. Zeroing out hundreds or thousands of GiB in a single core > memset() call is very slow, and can make early boot last upwards of > 20-30 minutes on multi TiB machines. > > To be safe, still zero the first sizeof(struct boomem_huge_page) bytes > since this is used a temporary storage place for this info until > gather_bootmem_prealloc() processes them later. > > The rest of the memory does not need to be zero'd as the hugetlb pages > are always zero'd on page fault. > > Tested: Booted with ~3800 1G pages, and it booted successfully in > roughly the same amount of time as with 0, as opposed to the 25+ > minutes it would take before. >
Nice improvement! > Signed-off-by: Cannon Matthews <[email protected]> > --- > mm/hugetlb.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 3612fbb32e9d..c93a2c77e881 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -2101,7 +2101,7 @@ int __alloc_bootmem_huge_page(struct hstate *h) > for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) { > void *addr; > > - addr = memblock_virt_alloc_try_nid_nopanic( > + addr = memblock_virt_alloc_try_nid_raw( > huge_page_size(h), huge_page_size(h), > 0, BOOTMEM_ALLOC_ACCESSIBLE, node); > if (addr) { > @@ -2109,7 +2109,12 @@ int __alloc_bootmem_huge_page(struct hstate *h) > * Use the beginning of the huge page to store the > * huge_bootmem_page struct (until gather_bootmem > * puts them into the mem_map). > + * > + * memblock_virt_alloc_try_nid_raw returns non-zero'd > + * memory so zero out just enough for this struct, the > + * rest will be zero'd on page fault. > */ > + memset(addr, 0, sizeof(struct huge_bootmem_page)); This forced me to look at the usage of huge_bootmem_page. It is defined as: struct huge_bootmem_page { struct list_head list; struct hstate *hstate; #ifdef CONFIG_HIGHMEM phys_addr_t phys; #endif }; The list and hstate fields are set immediately after allocating the memory block here and elsewhere. However, I can't find any code that sets phys. Although, it is potentially used in gather_bootmem_prealloc(). It appears powerpc used this field at one time, but no longer does. Am I missing something? Not an issue with this patch, rather existing code. I'd prefer not to do the memset() "just to be safe". Unless I am missing something, I would like to remove phys field and supporting code first. Then, this patch without the memset. -- Mike Kravetz > m = addr; > goto found; > } > -- > 2.18.0.203.gfac676dfb9-goog >
