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Refine docs.

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Stephen Chung
2020-09-19 12:14:02 +08:00
parent b795ce9f45
commit 2ff3a1fde5
18 changed files with 133 additions and 107 deletions
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doc/src/start/builds/performance.md
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@@ -13,23 +13,26 @@ If only a single integer type is needed in scripts - most of the time this is th
lots of functions related to other integer types that will never be used. As a result, [`Engine`] creation will be faster
because fewer functions need to be loaded.
The [`only_i32`] and [`only_i64`] features disable all integer types except `i32` or `i64` respectively.
Use Only 32-Bit Numbers
----------------------
If only 32-bit integers are needed - again, most of the time this is the case - using [`only_i32`] disables also `i64`.
If only 32-bit integers are needed - again, most of the time this is the case - turn on [`only_i32`].
Under this feature, only `i32` is supported as a built-in integer type and no others.
On 64-bit targets this may not gain much, but on some 32-bit targets this improves performance due to 64-bit arithmetic
requiring more CPU cycles to complete.
On 64-bit targets this may not gain much, but on certain 32-bit targets this improves performance
due to 64-bit arithmetic requiring more CPU cycles to complete.
Minimize Size of `Dynamic`
-------------------------
Turning on [`no_float`], and [`only_i32`] makes the key [`Dynamic`] data type only 8 bytes small on 32-bit targets
while normally it can be up to 16 bytes (e.g. on x86/x64 CPU's) in order to hold an `i64` or `f64`.
Turning on [`no_float`] and [`only_i32`] on 32-bit targets makes the critical [`Dynamic`] data type only 8 bytes long.
Normally [`Dynamic`] can be up to 16 bytes (e.g. on x86/x64 CPU's) in order to hold an `i64` or `f64`.
Making [`Dynamic`] small helps performance due to better cache efficiency.
A small [`Dynamic`] helps performance due to better cache efficiency.
Use `ImmutableString`
@@ -41,17 +44,17 @@ cloning when passing function arguments.
Rhai's internal string type is `ImmutableString` (basically `Rc<String>` or `Arc<String>` depending on the [`sync`] feature).
It is cheap to clone, but expensive to modify (a new copy of the string must be made in order to change it).
Therefore, functions taking `String` parameters should use `ImmutableString` or `&str` (which maps to `ImmutableString`)
Therefore, functions taking `String` parameters should use `ImmutableString` or `&str` (both map to `ImmutableString`)
for the best performance with Rhai.
Disable Closures
----------------
Support for [closures], including capturing shared values, adds material overhead to script evaluation.
Support for [closures] that capture shared variables adds material overhead to script evaluation.
This is because every data access must be checked whether it is a shared value, and if so, take a read
or write lock before reading it.
This is because every data access must be checked whether it is a shared value and, if so, take a read
lock before reading it.
Use [`no_closure`] to disable closure and capturing support and optimize the hot path
Use [`no_closure`] to disable closure and capturing support to optimize the hot path
because there is no need to take locks for shared data.