| Message ID | 20201026145114.59424-4-songmuchun@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Free some vmemmap pages of hugetlb page | expand |
On Mon, Oct 26, 2020 at 10:50:58PM +0800, Muchun Song wrote: > The purpose of introducing HUGETLB_PAGE_FREE_VMEMMAP is to configure > whether to enable the feature of freeing unused vmemmap associated > with HugeTLB pages. Now only support x86. Why this needs to be a config thing? If this space-memory-optimization does not come with a trade-off, why does the user have to set this instead of coming by default?
On Thu, Oct 29, 2020 at 6:29 PM Oscar Salvador <osalvador@suse.de> wrote: > > On Mon, Oct 26, 2020 at 10:50:58PM +0800, Muchun Song wrote: > > The purpose of introducing HUGETLB_PAGE_FREE_VMEMMAP is to configure > > whether to enable the feature of freeing unused vmemmap associated > > with HugeTLB pages. Now only support x86. > > Why this needs to be a config thing? > If this space-memory-optimization does not come with a trade-off, > why does the user have to set this instead of coming by default? Now we only support x86_64. If we want to support other archs. We need some arch special code to support this feature. In the future, if this patch series is merged to mainline, I will implement this optimization for other archs. At that time we can remove the HUGETLB_PAGE_FREE_VMEMMAP. Thanks. > > > -- > Oscar Salvador > SUSE L3
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 0a45f062826e..0435bee2e172 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1225,7 +1225,7 @@ static struct kcore_list kcore_vsyscall; static void __init register_page_bootmem_info(void) { -#ifdef CONFIG_NUMA +#if defined(CONFIG_NUMA) || defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP) int i; for_each_online_node(i) diff --git a/fs/Kconfig b/fs/Kconfig index 976e8b9033c4..5a4265ff2a86 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -245,6 +245,22 @@ config HUGETLBFS config HUGETLB_PAGE def_bool HUGETLBFS +config HUGETLB_PAGE_FREE_VMEMMAP + bool "Free unused vmemmap associated with HugeTLB pages" + default n + depends on X86 + depends on HUGETLB_PAGE + depends on SPARSEMEM_VMEMMAP + depends on HAVE_BOOTMEM_INFO_NODE + help + There are many struct page structures associated with each HugeTLB + page. But we only use a few struct page structures. In this case, + it wastes some memory. It is better to free the unused struct page + structures to buddy system which can save some memory. For + architectures that support it, say Y here. + + If unsure, say N. + config MEMFD_CREATE def_bool TMPFS || HUGETLBFS
The purpose of introducing HUGETLB_PAGE_FREE_VMEMMAP is to configure whether to enable the feature of freeing unused vmemmap associated with HugeTLB pages. Now only support x86. Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- arch/x86/mm/init_64.c | 2 +- fs/Kconfig | 16 ++++++++++++++++ 2 files changed, 17 insertions(+), 1 deletion(-)