diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 17 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/hugetlbpage.rst | 3 | ||||
| -rw-r--r-- | arch/x86/mm/init_64.c | 8 | ||||
| -rw-r--r-- | include/linux/hugetlb.h | 19 | ||||
| -rw-r--r-- | mm/hugetlb_vmemmap.c | 24 |
5 files changed, 69 insertions, 2 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 566c4b9af3cd..b787a9953f2e 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1567,6 +1567,23 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_free_vmemmap= + [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + enabled. + Allows heavy hugetlb users to free up some more + memory (6 * PAGE_SIZE for each 2MB hugetlb page). + This feauture is not free though. Large page + tables are not used to back vmemmap pages which + can lead to a performance degradation for some + workloads. Also there will be memory allocation + required when hugetlb pages are freed from the + pool which can lead to corner cases under heavy + memory pressure. + Format: { on | off (default) } + + on: enable the feature + off: disable the feature + hung_task_panic= [KNL] Should the hung task detector generate panics. Format: 0 | 1 diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst index 6988895d09a8..8abaeb144e44 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -153,6 +153,9 @@ default_hugepagesz will all result in 256 2M huge pages being allocated. Valid default huge page size is architecture dependent. +hugetlb_free_vmemmap + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing + unused vmemmap pages associated with each HugeTLB page. When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` indicates the current number of pre-allocated huge pages of the default size. diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 65ea58527176..9d9d18d0c2a1 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -34,6 +34,7 @@ #include <linux/gfp.h> #include <linux/kcore.h> #include <linux/bootmem_info.h> +#include <linux/hugetlb.h> #include <asm/processor.h> #include <asm/bios_ebda.h> @@ -1609,7 +1610,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE)); VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE)); - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) + if ((is_hugetlb_free_vmemmap_enabled() && !altmap) || + end - start < PAGES_PER_SECTION * sizeof(struct page)) err = vmemmap_populate_basepages(start, end, node, NULL); else if (boot_cpu_has(X86_FEATURE_PSE)) err = vmemmap_populate_hugepages(start, end, node, altmap); @@ -1637,6 +1639,8 @@ void register_page_bootmem_memmap(unsigned long section_nr, pmd_t *pmd; unsigned int nr_pmd_pages; struct page *page; + bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) || + is_hugetlb_free_vmemmap_enabled(); for (; addr < end; addr = next) { pte_t *pte = NULL; @@ -1662,7 +1666,7 @@ void register_page_bootmem_memmap(unsigned long section_nr, } get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO); - if (!boot_cpu_has(X86_FEATURE_PSE)) { + if (base_mapping) { next = (addr + PAGE_SIZE) & PAGE_MASK; pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 3578d9d708fe..9ad99848f9f0 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -892,6 +892,20 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, } #endif +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +extern bool hugetlb_free_vmemmap_enabled; + +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return hugetlb_free_vmemmap_enabled; +} +#else +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return false; +} +#endif + #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; @@ -1046,6 +1060,11 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr pte_t *ptep, pte_t pte, unsigned long sz) { } + +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return false; +} #endif /* CONFIG_HUGETLB_PAGE */ static inline spinlock_t *huge_pte_lock(struct hstate *h, diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index a897c7778246..3070e1465b1b 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -168,6 +168,8 @@ * (last) level. So this type of HugeTLB page can be optimized only when its * size of the struct page structs is greater than 2 pages. */ +#define pr_fmt(fmt) "HugeTLB: " fmt + #include "hugetlb_vmemmap.h" /* @@ -180,6 +182,28 @@ #define RESERVE_VMEMMAP_NR 2U #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) +bool hugetlb_free_vmemmap_enabled; + +static int __init early_hugetlb_free_vmemmap_param(char *buf) +{ + /* We cannot optimize if a "struct page" crosses page boundaries. */ + if ((!is_power_of_2(sizeof(struct page)))) { + pr_warn("cannot free vmemmap pages because \"struct page\" crosses page boundaries\n"); + return 0; + } + + if (!buf) + return -EINVAL; + + if (!strcmp(buf, "on")) + hugetlb_free_vmemmap_enabled = true; + else if (strcmp(buf, "off")) + return -EINVAL; + + return 0; +} +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); + static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hstate *h) { return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT; |