Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 4 Apr 2022 14:56:17 +0530 | Subject | Re: [PATCH v4 2/2] arm64: mm: hugetlb: Enable HUGETLB_PAGE_FREE_VMEMMAP for arm64 | From | Anshuman Khandual <> |
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Hello Muchun,
On 3/31/22 12:26, Muchun Song wrote: > The feature of minimizing overhead of struct page associated with each > HugeTLB page aims to free its vmemmap pages (used as struct page) to > save memory, where is ~14GB/16GB per 1TB HugeTLB pages (2MB/1GB type).
Enabling this feature saves us around 1.4/1.6 % memory but looking from other way around, unavailability of vmemmap backing pages (~1.4GB) when freeing up a corresponding HugeTLB page, could prevent ~1TB memory from being used as normal page form (requiring their own struct pages), thus forcing the HugeTLB page to remain as such ? Is not this problematic ?
These additional 1TB memory in normal pages, from a HugeTLB dissolution could have eased the system's memory pressure without this feature being enabled.
- Anshuman
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