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* Don't reexport types from `wasmtime_runtime` from the `wasmtime` crate.
* Add more comments.
This commit is contained in:
Peter Huene
2021-03-04 22:27:27 -08:00
parent ff840b3d3b
commit a4084db096
3 changed files with 241 additions and 53 deletions
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6
crates/runtime/src/instance.rs
View File

@@ -381,7 +381,11 @@ impl Instance {
/// Returns `None` if memory can't be grown by the specified amount
/// of pages.
pub(crate) fn memory_grow(&self, memory_index: DefinedMemoryIndex, delta: u32) -> Option<u32> {
// Reset all guard pages before growing any memory
// Reset all guard pages before growing any memory when using the uffd feature.
// The uffd feature induces a trap when a fault on a linear memory page is determined to be out-of-bounds.
// It does this by temporarily setting the protection level to `NONE` to cause the kernel to signal SIGBUS.
// Because instances might still be used after a trap, this resets the page back to the expected protection
// level (READ_WRITE) for the uffd implementation.
#[cfg(all(feature = "uffd", target_os = "linux"))]
self.reset_guard_pages().ok()?;

60
crates/runtime/src/instance/allocator/pooling.rs
View File

@@ -55,53 +55,37 @@ fn round_up_to_pow2(n: usize, to: usize) -> usize {
/// Represents the limits placed on a module for compiling with the pooling instance allocator.
#[derive(Debug, Copy, Clone)]
pub struct ModuleLimits {
/// The maximum number of imported functions for a module (default is 1000).
/// The maximum number of imported functions for a module.
pub imported_functions: u32,
/// The maximum number of imported tables for a module (default is 0).
/// The maximum number of imported tables for a module.
pub imported_tables: u32,
/// The maximum number of imported linear memories for a module (default is 0).
/// The maximum number of imported linear memories for a module.
pub imported_memories: u32,
/// The maximum number of imported globals for a module (default is 0).
/// The maximum number of imported globals for a module.
pub imported_globals: u32,
/// The maximum number of defined types for a module (default is 100).
/// The maximum number of defined types for a module.
pub types: u32,
/// The maximum number of defined functions for a module (default is 10000).
/// The maximum number of defined functions for a module.
pub functions: u32,
/// The maximum number of defined tables for a module (default is 1).
/// The maximum number of defined tables for a module.
pub tables: u32,
/// The maximum number of defined linear memories for a module (default is 1).
/// The maximum number of defined linear memories for a module.
pub memories: u32,
/// The maximum number of defined globals for a module (default is 10).
/// The maximum number of defined globals for a module.
pub globals: u32,
/// The maximum table elements for any table defined in a module (default is 10000).
///
/// If a table's minimum element limit is greater than this value, the module will
/// fail to compile.
///
/// If a table's maximum element limit is unbounded or greater than this value,
/// the maximum will be `table_elements` for the purpose of any `table.grow` instruction.
/// The maximum table elements for any table defined in a module.
pub table_elements: u32,
/// The maximum number of pages for any linear memory defined in a module (default is 160).
///
/// The default of 160 means at most 10 MiB of host memory may be committed for each instance.
///
/// If a memory's minimum page limit is greater than this value, the module will
/// fail to compile.
///
/// If a memory's maximum page limit is unbounded or greater than this value,
/// the maximum will be `memory_pages` for the purpose of any `memory.grow` instruction.
///
/// This value cannot exceed any memory reservation size limits placed on instances.
/// The maximum number of pages for any linear memory defined in a module.
pub memory_pages: u32,
}
@@ -224,7 +208,7 @@ impl ModuleLimits {
impl Default for ModuleLimits {
fn default() -> Self {
// See doc comments for `ModuleLimits` for these default values
// See doc comments for `wasmtime::ModuleLimits` for these default values
Self {
imported_functions: 1000,
imported_tables: 0,
@@ -244,32 +228,16 @@ impl Default for ModuleLimits {
/// Represents the limits placed on instances by the pooling instance allocator.
#[derive(Debug, Copy, Clone)]
pub struct InstanceLimits {
/// The maximum number of concurrent instances supported (default is 1000).
/// The maximum number of concurrent instances supported.
pub count: u32,
/// The maximum size, in bytes, of host address space to reserve for each linear memory of an instance.
///
/// Note: this value has important performance ramifications.
///
/// On 64-bit platforms, the default for this value will be 6 GiB. A value of less than 4 GiB will
/// force runtime bounds checking for memory accesses and thus will negatively impact performance.
/// Any value above 4 GiB will start eliding bounds checks provided the `offset` of the memory access is
/// less than (`memory_reservation_size` - 4 GiB). A value of 8 GiB will completely elide *all* bounds
/// checks; consequently, 8 GiB will be the maximum supported value. The default of 6 GiB reserves
/// less host address space for each instance, but a memory access with an offet above 2 GiB will incur
/// runtime bounds checks.
///
/// On 32-bit platforms, the default for this value will be 10 MiB. A 32-bit host has very limited address
/// space to reserve for a lot of concurrent instances. As a result, runtime bounds checking will be used
/// for all memory accesses. For better runtime performance, a 64-bit host is recommended.
///
/// This value will be rounded up by the WebAssembly page size (64 KiB).
pub memory_reservation_size: u64,
}
impl Default for InstanceLimits {
fn default() -> Self {
// See doc comments for `InstanceLimits` for these default values
// See doc comments for `wasmtime::InstanceLimits` for these default values
Self {
count: 1000,
#[cfg(target_pointer_width = "32")]