Messages in this thread | | | Date | Wed, 8 May 2024 13:45:48 +0800 | Subject | Re: [PATCH 0/8] add mTHP support for anonymous shmem | From | Baolin Wang <> |
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On 2024/5/7 18:20, Ryan Roberts wrote: > On 06/05/2024 09:46, Baolin Wang wrote: >> Anonymous pages have already been supported for multi-size (mTHP) allocation >> through commit 19eaf44954df, that can allow THP to be configured through the >> sysfs interface located at '/sys/kernel/mm/transparent_hugepage/hugepage-XXkb/enabled'. >> >> However, the anonymous shared pages will ignore the anonymous mTHP rule >> configured through the sysfs interface, and can only use the PMD-mapped >> THP, that is not reasonable. Many implement anonymous page sharing through >> mmap(MAP_SHARED | MAP_ANONYMOUS), especially in database usage scenarios, >> therefore, users expect to apply an unified mTHP strategy for anonymous pages, >> also including the anonymous shared pages, in order to enjoy the benefits of >> mTHP. For example, lower latency than PMD-mapped THP, smaller memory bloat >> than PMD-mapped THP, contiguous PTEs on ARM architecture to reduce TLB miss etc. >> >> The primary strategy is similar to supporting anonymous mTHP. Introduce >> a new interface '/mm/transparent_hugepage/hugepage-XXkb/shmem_enabled', >> which can have all the same values as the top-level > > Didn't we agree that "force" would not be supported for now, and would return an > error when attempting to set for a non-PMD-size hugepage-XXkb/shmem_enabled (or > indirectly through inheritance)?
Yes. Sorry, I did not explain it in detail in the cover letter. Please see patch 5 you already commented.
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