Wasmtime GitHub notifications bot (Jan 30 2023 at 22:48): Wasmtime GitHub notifications bot (Jan 30 2023 at 22:48):github-actions[bot] commented on issue #5656:
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Wasmtime GitHub notifications bot (Jan 30 2023 at 22:48):github-actions[bot] commented on issue #5656:
Label Messager: wasmtime:config
It looks like you are changing Wasmtime's configuration options. Make sure to
complete this check list:
[ ] If you added a new
Configmethod, you wrote extensive documentation for
it.<details>
Our documentation should be of the following form:
```text
Short, simple summary sentence.More details. These details can be multiple paragraphs. There should be
information about not just the method, but its parameters and results as
well.Is this method fallible? If so, when can it return an error?
Can this method panic? If so, when does it panic?
Example
Optional example here.
```</details>
[ ] If you added a new
Configmethod, or modified an existing one, you
ensured that this configuration is exercised by the fuzz targets.<details>
For example, if you expose a new strategy for allocating the next instance
slot inside the pooling allocator, you should ensure that at least one of our
fuzz targets exercises that new strategy.Often, all that is required of you is to ensure that there is a knob for this
configuration option in [wasmtime_fuzzing::Config][fuzzing-config] (or one
of its nestedstructs).Rarely, this may require authoring a new fuzz target to specifically test this
configuration. See [our docs on fuzzing][fuzzing-docs] for more details.</details>
[ ] If you are enabling a configuration option by default, make sure that it
has been fuzzed for at least two weeks before turning it on by default.[fuzzing-config]: https://github.com/bytecodealliance/wasmtime/blob/ca0e8d0a1d8cefc0496dba2f77a670571d8fdcab/crates/fuzzing/src/generators.rs#L182-L194
[fuzzing-docs]: https://docs.wasmtime.dev/contributing-fuzzing.html
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Wasmtime GitHub notifications bot (Feb 01 2023 at 17:54):alexcrichton commented on issue #5656:
what is the point of pooling?
In my head the main purpose of pooling in Wasmtime is to reduce the impact of virtual memory management. Reusing slots allows memory image reuse possibly, reduction of page faults as memory is already paged in, etc.
Precisely how the pool is used I think is up to an application. For example an application may want a large pool for a smaller number of maximally concurrent instances to have as many affine slots per module as possible. In such a configuration it may not be expected to have such a large impact on RSS for idle slots doing nothing.
Overall I personally think it's pretty reasonable to expect that the working set consumed by wasmtime is roughly proportional to the working set of live objects in an embedding. While it's not strictly necessary that we malloc/free the instances here I don't think it necessarily hurts anyone.
The changes here can have other minor additional benefits such reducing fragmentation overhead since instances are allocated on page-aligned mappings today whereas with this PR they're thrown into the general malloc/free pool to get a better fit.
Last updated: Dec 23 2024 at 13:07 UTC