| Message ID | 20201210035526.38938-10-songmuchun@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Free some vmemmap pages of HugeTLB page | expand |
On Thu, Dec 10, 2020 at 11:55:23AM +0800, Muchun Song wrote: > +hugetlb_free_vmemmap > + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing > + unused vmemmap pages associated each HugeTLB page. ^^^ with > - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) > + if (is_hugetlb_free_vmemmap_enabled()) > + err = vmemmap_populate_basepages(start, end, node, NULL); > + else if (end - start < PAGES_PER_SECTION * sizeof(struct page)) > err = vmemmap_populate_basepages(start, end, node, NULL); Not sure if joining those in an OR makes se.se > else if (boot_cpu_has(X86_FEATURE_PSE)) > err = vmemmap_populate_hugepages(start, end, node, altmap); > @@ -1610,7 +1613,8 @@ 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 (!boot_cpu_has(X86_FEATURE_PSE) || > + is_hugetlb_free_vmemmap_enabled()) { I would add a variable at the beginning called "basepages_populated" that holds the result of those two conditions. I am not sure if it slightly improves the code as the conditions do not need to be rechecked, but the readibility a bit. > +bool hugetlb_free_vmemmap_enabled; > + > +static int __init early_hugetlb_free_vmemmap_param(char *buf) > +{ > + if (!buf) > + return -EINVAL; > + > + /* We cannot optimize if a "struct page" crosses page boundaries. */ I think this comment belongs to the last patch.
On Thu, Dec 10, 2020 at 7:41 PM Oscar Salvador <osalvador@suse.de> wrote: > > On Thu, Dec 10, 2020 at 11:55:23AM +0800, Muchun Song wrote: > > +hugetlb_free_vmemmap > > + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing > > + unused vmemmap pages associated each HugeTLB page. > ^^^ with Thanks. > > > - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) > > + if (is_hugetlb_free_vmemmap_enabled()) > > + err = vmemmap_populate_basepages(start, end, node, NULL); > > + else if (end - start < PAGES_PER_SECTION * sizeof(struct page)) > > err = vmemmap_populate_basepages(start, end, node, NULL); > > Not sure if joining those in an OR makes se.se Well, I can do it. > > > else if (boot_cpu_has(X86_FEATURE_PSE)) > > err = vmemmap_populate_hugepages(start, end, node, altmap); > > @@ -1610,7 +1613,8 @@ 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 (!boot_cpu_has(X86_FEATURE_PSE) || > > + is_hugetlb_free_vmemmap_enabled()) { > > I would add a variable at the beginning called "basepages_populated" > that holds the result of those two conditions. > I am not sure if it slightly improves the code as the conditions do > not need to be rechecked, but the readibility a bit. Agree. The condition does not need to be rechecked. Will do in the next version. Thanks. > > > +bool hugetlb_free_vmemmap_enabled; > > + > > +static int __init early_hugetlb_free_vmemmap_param(char *buf) > > +{ > > + if (!buf) > > + return -EINVAL; > > + > > + /* We cannot optimize if a "struct page" crosses page boundaries. */ > > I think this comment belongs to the last patch. > Thanks. > > -- > Oscar Salvador > SUSE L3
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3ae25630a223..9e6854f21d55 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1551,6 +1551,15 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_free_vmemmap= + [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, + this controls freeing unused vmemmap pages associated + with each HugeTLB page. + 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 f7b1c7462991..6a8b57f6d3b7 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -145,6 +145,9 @@ 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 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 0435bee2e172..fcdc020904a8 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> @@ -1557,7 +1558,9 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, { int err; - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) + if (is_hugetlb_free_vmemmap_enabled()) + err = vmemmap_populate_basepages(start, end, node, NULL); + else if (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); @@ -1610,7 +1613,8 @@ 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 (!boot_cpu_has(X86_FEATURE_PSE) || + is_hugetlb_free_vmemmap_enabled()) { 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 ebca2ef02212..7f47f0eeca3b 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -770,6 +770,20 @@ 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 {}; @@ -923,6 +937,11 @@ 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 4587a0062808..f0926b382338 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -204,6 +204,22 @@ typedef void (*vmemmap_remap_pte_func_t)(struct page *reuse, pte_t *pte, unsigned long start, unsigned long end, void *priv); +bool hugetlb_free_vmemmap_enabled; + +static int __init early_hugetlb_free_vmemmap_param(char *buf) +{ + if (!buf) + return -EINVAL; + + /* We cannot optimize if a "struct page" crosses page boundaries. */ + 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 int vmemmap_pages_per_hpage(struct hstate *h) {
Add a kernel parameter hugetlb_free_vmemmap to disable the feature of freeing unused vmemmap pages associated with each hugetlb page on boot. Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ arch/x86/mm/init_64.c | 8 ++++++-- include/linux/hugetlb.h | 19 +++++++++++++++++++ mm/hugetlb_vmemmap.c | 16 ++++++++++++++++ 5 files changed, 53 insertions(+), 2 deletions(-)