Set EOS VM OC max mirroring pages to a small number for read-only threads #1488
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heifner
requested changes
Aug 14, 2023
heifner
approved these changes
Aug 14, 2023
spoonincode
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Aug 14, 2023
| // Set mirroring_pages_for_ro_thread to a small number to save upfront virtual memory | ||
| // consumption. Usage beyond this limit will be handled by mprotect. | ||
| constexpr uint32_t mirroring_pages_for_ro_thread = 10; | ||
| thread_local eosvmoc::memory eosvmoc_runtime::mem_thread_local{mirroring_pages_for_ro_thread}; |
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I'm kind of surprised this works... but best I can tell from reading the code thoroughly is that it does what we want correctly.
I may suggest we change the name of the ctor parameter,
from
max_pages to sliced_pages (or something else). It probably was "max pages" in 2.0, but its meaning has changed in 2.1/3.0.5.
I'd also suggest we remove
afaict it isn't used (I removed it locally and the build worked at least).
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Thanks. I made the suggested changes. The code is even cleaner.
…ed_pages and delete unused memory::reset(uint64_t max_pages)
spoonincode
approved these changes
Aug 14, 2023
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A part of eosnetworkfoundation/product#149.
Per the design in https://github.com/eosnetworkfoundation/product/blob/main/transactions/read-only/memory.md, to conserve virtual memory to support more threads, we need to reduce the threshold where EOS VM OC transitions from mirroring to
mprotect().We plan to keep 528 pages (529 slices) for the main-thread memory (currently used for anything other then read-only transaction threads); this ensures maximum performance for EVM transactions. For each read-only thread, we set 10 pages (11 slices) (10 pages covers 99% native actions and 56% EVM actions, from data collected by in #1159).
With maximum 256 read-only threads , virtual memory required by OC is 26 TB (OC's main thread uses 4TB VM (by 529 slices) and the read-only threads use 22TB (256 * 11 * 8GB)). It is about 20% of total VM space in a 64-bit Linux machine (about 128TB).
The coding is much simpler.
Resolves #645