Open Bug 2022623 Opened 4 months ago Updated 4 months ago

[meta] lazy-collections in JS3 is slow

Categories

(Core :: JavaScript Engine, task, P3)

Product:
Core
Component:
JavaScript Engine
Type:
task

Tracking

()

People

(Reporter: mgaudet, Unassigned)

References

(Depends on 1 open bug, Blocks 1 open bug)

Details

(Keywords: meta)

Relative to other engines, lazy-collections is relatively slow (~55% on a mac)

Note: This is a generators benchmark. 18% of time is spent in GeneratorNext .

Run it by itself via https://webkit-jetstream-preview.netlify.app/?test=lazy-collections&prefetchResources=false

If I compare shell profiles of V8 and SM: we spend ~9400 samples in GeneratorNext, while V8 spends around 2500. But this may be somewhat misleading: we spend ~2800 samples in range, while V8 spends 5000. Part of the difference is that we restore generator state on the caller side in GeneratorNext, while V8 does it callee-side.

It's worth noting that turning off turbofan doesn't hurt V8's performance much, so it's not clear that Ion-optimized generators are the key here.

Severity: -- → N/A
Priority: -- → P3
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