1603453 - When the CPU is under load posting tasks to the renderer thread's eventloop can take a long time

Status: NEW

(Core :: Graphics: WebRender, defect, P3)

Description

[Nicolas Silva [:nical]]

profiling scrolling a bugzilla page while CPU under load (during clobber build on an xps13 laptop). we spend 6% of the frame building time posting a task to the renderer thread's event loop (mostly in _pthread_mutex_unlock_usercnt).

More generally anything that forces us to block on a mutex or condition variable takes a long time when the CPU is under load (27% in rayon_core::registry::Registry::inject_or_push !).