On Aug 28, 2018, at 11:25 AM, Yusuke Suzuki <yusukesuzuki@slowstart.org> wrote:
Thanks!
On Wed, Aug 29, 2018 at 3:22 Filip Pizlo <fpizlo@apple.com <mailto:fpizlo@apple.com>> wrote: I don’t like this proposal.
If we are running low on memory, we should switch to bounds checked memory.
How about using bound checking mode exclusively for low environment?
That would mean that, paradoxically, having a machine with a lot of memory means being able to spawn fewer wasm instances. We want to support lightweight wasm instances because it wouldn’t be good to rule that out as a use case. -Filip
-Filip
On Aug 28, 2018, at 11:21 AM, Yusuke Suzuki <yusukesuzuki@slowstart.org <mailto:yusukesuzuki@slowstart.org>> wrote:
Posted this mail to webkit-dev mailing list too :)
On Wed, Aug 29, 2018 at 3:19 AM Yusuke Suzuki <yusukesuzuki@slowstart.org <mailto:yusukesuzuki@slowstart.org>> wrote: Hi JSC folks,
In Wasm supported environment, our MemoryMode is a bit dynamic. When we fail to allocate WasmMemory for signaling mode, we fall back to the bound checking memory instead.
But Wasm code compiled for signaling / bound checking is incompatible. If the code is compiled as signaling mode, and if we attach the memory for bound checking, we need to recompile the code for bound checking mode. This introduces significant complexity to our wasm compilation. And our WebAssembly.compile is not basically compiling: it is just validating. Actual compiling needs to be deferred until the memory is attached by instantiating. It is not good when we would like to share WasmModule among multiple wasm threads / workers in the future, since the "compiled" Wasm module is not actually compiled.
So, my proposal is, can we explore the way to exclusively support one of MemoryMode in a certain architecture? For example, in x64, enable signaling mode, and we report OOM errors if we fail to allocate WasmMemory with signaling mode.
Best regards, Yusuke Suzuki
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