wasmtime: Cache VMFuncRef in component::Func - #14189
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A core `Func` caches a raw pointer to its `VMFuncRef`, but a `component::Func` rederives the pointer on ever call and this contributes to host -> wasm component function calls having significantly higher overhead than core function calls (even concurrency support disabled). This PR caches the `VMFuncRef` for `component::Func` in the same it is currently done for core `Func`. The `VMFuncRef` for the associated `post_return` call is also cached along with Some additional metadata. These are my benchmark results for the impact on nop calls with no arguments or return values: Before change: | Call type | Latency | ----------------------------------------------- | core | 35 ns | | component (concurrency disabled) | 300 ns | | component (concurrency enabled) | 800 ns | After change: | Call type | Latency | ----------------------------------------------- | core | 35 ns | | component (concurrency disabled) | 140 ns | | component (concurrency enabled) | 600 ns | The bencmarks run are: ``` cargo bench --bench call -- --exact "sync/no-hook/core - host-to-wasm - typed - nop" cargo bench --bench call -- --exact "no-concurrent/sync/no-hook/component - host-to-wasm - typed - nop" cargo bench --bench call -- --exact "concurrent/sync/no-hook/component - host-to-wasm - typed - nop" ```
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A core
Funccaches a raw pointer to itsVMFuncRef, but acomponent::Funcrederives the pointer on ever call and thiscontributes to host -> wasm component function calls having
significantly higher overhead than core function calls (even concurrency
support disabled).
This PR caches the
VMFuncRefforcomponent::Funcin the same it iscurrently done for core
Func. TheVMFuncReffor the associatedpost_returncall is also cached along with Some additional metadata.These are my benchmark results for the impact on nop calls with no
arguments or return values:
Before change:
After change:
The bencmarks run are:
A separate commit also modifies the
callbenchmark to allow running component calls without concurrency support.