1611176 - Expensive moves of RenderTask into the tasks vector

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect)

Description

[Nicolas Silva [:nical]]

We get a non-trivial amount of time spent in memmove when pushing render tasks into the render graph (5% of total frame building time on a test case with a large amount of text shadows).

We can work around this using the VecHelper trick add().init(value) which performs the potential reallocation before initializing the value.

Comment 1

[Nicolas Silva [:nical]]

Attachment: Bug 1611176 - Avoid expensive memmoves when adding render tasks. r=gw

On pages with many render tasks (typically a lot of text shadows), we spend a lot of time moving RenderTask which is a fairly large struct into the render graph's buffer. This patch avoids it by using the VecHelper trick of allocaitng space before initializing the value. Some RenderTask::new_* methods which take the render task graph in parameter were modified to add the task and return the task ID to work around borrow-checking restriction.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e30053699db0
Avoid expensive memmoves when adding render tasks. r=gw

Comment 3

[Razvan Maries]

https://hg.mozilla.org/mozilla-central/rev/e30053699db0