On October 12, 2021 6:39 PM, Gerd Hoffmann wrote: > Hi, > > > - AcceptPages: > > To mitigate the performance impact of accepting pages in SEC phase on > > BSP, BSP will parse memory resources and assign each AP the task of > > accepting a subset of pages. This command may be called several times > > until all memory resources are processed. In accepting pages, PageLevel > > may fall back to smaller one if SIZE_MISMATCH error is returned. > > Hmm, I'm wondering whenever it is useful to have this in the first place with > the longer-term plan to implement lazy on-demand acceptance. To mitigate the performance impact of accepting pages, there are 3 ways. 1. Big accept page size. 2. Accept the pages by BSP and APs together. 3. Lazy on-demand acceptance. >From the perspective of implementation complexity, 1 < 2 < 3. Lazy on-demand acceptance need the update not only in TDVF, but also in Guest kernel. More investigation shows it also impacts the grub and memory management in EDK2. >From the perspective of performance improvement, 2M accept page size + BSP/AP >together, can improve the performance a lot. Based on above consideration, in current TDVF upstream, 1 + 2 are the ways to mitigate the performance impact. Upstream of 3 is in the future plan.
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