1912019 - Experiment with a custom allocator for the contents of the built frame

Status: RESOLVED FIXED

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

Description

[Nicolas Silva [:nical]]

The goal is to avoid expensive allocations in the frame builder thread and expensive deallocations on the renderer thread when the built frame is dropped.

The idea is to use simple and fast bump allocators to for anything that is allocated on the render backend thread, sent to the renderer and have the same lifetime as the frame (all of them are dropped along with the frame).

There are a fair amount of other types of allocations on the render backend thread (mostly longer lived allocations that stay on the RB thread to describe retained state and cached). These will not be affected by this work.

The WIP prototype uses allocator_api2.

Comment 1

[Nicolas Silva [:nical]]

Attachment: Bug 1912019 - Add a modified dependency to allocator_api2. r=glandium

Comment 2

[Nicolas Silva [:nical]]

Attachment: WIP: Bug 1912019 - WIP - Use FrameVec.

Comment 3

[Nicolas Silva [:nical]]

Attachment: Bug 1912019 - Add FrameAllocator, backed by a bump allocator. r=#gfx-reviewers

The safety of this allocator relies on it counting allocations and deallocations.
When the allocator is dropped or reset, the live allocation count is checked and failure to deallocate all live allocations in time crashes the process.
The allocator is created on the render backend thread, where allocations are made and sent along with the frame to the renderer thread where the frame is read. As soon as a new frame comes in to replace the current one, all of the current frame's allocations are dropped along with it. It is then safe to dispose of the allocator's memory or reset and reuse the allocator.
The allocator move between threads (along with its allocations) but is never used concurrently from multiple threads.

Depends on D218729

Comment 4

[Nicolas Silva [:nical]]

Attachment: Bug 1912019 - Use FrameVec for most of the frame's vectors. r=#gfx-reviewers

Depends on D219268

Comment 5

[Nicolas Silva [:nical]]

Attachment: Bug 1912019 - Don't use malloc_size_of for the render task graph. r=#gfx-reviewers

Attempting to use malloc_size_of with allocations that aren't directly backend by the global allocator crashes, so this commits compute the render task's report by in a more manual way.
In addition, add the allocator's memory footprint to memory reports.

Depends on D219269

Comment 6

[Nicolas Silva [:nical]]

Attachment: Bug 1912019 - Work around serde(skip). r=#gfx-reviewers

Depends on D219270

Comment 7

[Nicolas Silva [:nical]]

Attachment: Bug 1912019 - Undo the gpu-descriptor crate override. r=ErichDonGubler

WebRender depends on allocator-api2 now.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3521a2abcbfb
Add a modified dependency to allocator_api2. r=supply-chain-reviewers
https://hg.mozilla.org/integration/autoland/rev/f7a971f4161e
Add FrameAllocator, backed by a bump allocator. r=gfx-reviewers,lsalzman
https://hg.mozilla.org/integration/autoland/rev/30c81d683bef
Use FrameVec for most of the frame's vectors. r=gfx-reviewers,lsalzman
https://hg.mozilla.org/integration/autoland/rev/80057a2b320b
Don't use malloc_size_of for the render task graph. r=gfx-reviewers,lsalzman
https://hg.mozilla.org/integration/autoland/rev/e3195c10d336
Work around serde(skip). r=gfx-reviewers,lsalzman,ErichDonGubler
https://hg.mozilla.org/integration/autoland/rev/5c0408e2fee2
Undo the gpu-descriptor crate override. r=ErichDonGubler,supply-chain-reviewers

Comment 9

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/3521a2abcbfb
https://hg.mozilla.org/mozilla-central/rev/f7a971f4161e
https://hg.mozilla.org/mozilla-central/rev/30c81d683bef
https://hg.mozilla.org/mozilla-central/rev/80057a2b320b
https://hg.mozilla.org/mozilla-central/rev/e3195c10d336
https://hg.mozilla.org/mozilla-central/rev/5c0408e2fee2