1385159 - Use autoarryay to prevent buffer allocation in DrawTargetSkia::DrawGlyphs

Status: RESOLVED FIXED

(Core :: Web Painting, defect)

Description

[u459114]

Attachment: Firefox 2017-07-28 10.17 profile.sps.json

While profing https://immersion.media.mit.edu/demo
In DrawTargetSkia::DrawGlyphs
vector::append spends 4.0ms + 7.0ms
arena_dalloc spends 4.0ms

Comment 1

[u459114]

Attachment: Bug 1385159 - Use array on the stack to prevent buffer allocation in DrawTargetSkia::DrawGlyphs.

Review commit: https://reviewboard.mozilla.org/r/162448/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/162448/

Comment 2

[u459114]

Attachment: Bug 1385159 - Use AutoArray to prevent buffer allocation in DrawTargetSkia::DrawGlyphs.

Replace std::vector by AutoArray to prevent heap allocation.
I set default size of these array by 512, since in practice, most strings are
shorter than 512.

Review commit: https://reviewboard.mozilla.org/r/162450/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/162450/

Comment 3

[u459114]

Comment on attachment 8891246 [details]
Bug 1385159 - Use array on the stack  to prevent buffer allocation in DrawTargetSkia::DrawGlyphs.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/162448/diff/1-2/

Comment 4

[Matt Woodrow (:mattwoodrow)]

Comment on attachment 8891246 [details]
Bug 1385159 - Use array on the stack  to prevent buffer allocation in DrawTargetSkia::DrawGlyphs.

https://reviewboard.mozilla.org/r/162448/#review168150

This seems like a lot of stack space to consume.

Do we have any data on how long strings normally are? Could we go shorter than 512 and still get most of the benefits?
I'd prefer if we could try minimize this, to reduce the chances of overflowing the stack.

Comment 5

[u459114]

Comment on attachment 8891246 [details]
Bug 1385159 - Use array on the stack  to prevent buffer allocation in DrawTargetSkia::DrawGlyphs.

https://reviewboard.mozilla.org/r/162448/#review168150

Mostly, < 64. Sometimes, between 64 and 128. > 128 is rare.

Comment 6

[u459114]

Comment on attachment 8891246 [details]
Bug 1385159 - Use array on the stack  to prevent buffer allocation in DrawTargetSkia::DrawGlyphs.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/162448/diff/2-3/

Comment 7

[u459114]

Comment on attachment 8891246 [details]
Bug 1385159 - Use array on the stack  to prevent buffer allocation in DrawTargetSkia::DrawGlyphs.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/162448/diff/3-4/

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0d32624a93df
Use array on the stack  to prevent buffer allocation in DrawTargetSkia::DrawGlyphs. r=mattwoodrow

Comment 9

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/0d32624a93df