Wednesday, February 18, 2015

Attendees: benjhayden, cbiesinger, dsinclair, eae, jchaffraix, nduca, szager, skobes, slightlyoff, hartmanng

Status updates:

Performance Tracking (benjhayden)

• Finished profiling most of the key silk test cases on android, added

more graphs and information to the profiling doc.

• Next up, classifying types of layout.

Scrolling (skobes) [crbug.com/417782]

• Smooth scrolling enabledd for RenderLayerScrollableArea.

• Fixed position elements.

win_blink flakiness (dsinclair)

• win_blink_rel now among the better bots in terms of flakiness.

• Slowly re-enabling tests, monitoring flakiness.

Rename Rendering -> Layout [crbug.com/450612] (dsinclair)

• Trying to rename RendereBlock to LayoutBlock. Involves 30k files which

rietveld does not like. Uploading for reviews cases the upload command

to crash.

List markers (dsinclair)

• Trying to figure out how to deal with an ancestor being moved.

Measure API (jchaffraix)

• Working on a number of prototypes for measure together with Ian

Kilpatrick.

• github repo for prototypes. To allow layout callbacks a script

execution context might be needed. Runs js in snadbox since we cannot

modify the DOM. Would not have even read-only access to the DOM.

Needs to be able to access render tree in a safe way.

• Defining an API for the render tree, houdini style.

• slightlyoff would prefer to not add a new execution context that is

not workers. jchaffraix and slightlyoff to talk offline.

Line Boxes (hartmanng, szager) [crbug.com/321237]

• No real progress last week. Blocked on higher priority work to fix

high profile regressions.

Flexbox (cbiesinger) [crbug.com/426898]

• Working on updating flexbox implementation to match latest spec

revision.

Text (kojii, eae)

• Made RenderCombinedText less obstructive. 4 if-RenderCombinedText

removed, 1 moved to less frequent path. (kojii)

• Worked with dominik.rottsches to make vertical flow performance

test. (kojii)

• Started analyzing complex path performance. It looks like

characteristics varies by scripts and values of properties. I'll look

into CJK vertical flow first. (kojii)

• Fixed two text regressions on Mac causing incorrect rendering and/or a

render crash (due to an ASSERT). Required a Harfbuzz change and roll.

(eae, behdad)

• Added support for emoticons and emoji on Windows. (eae)

Line layout (szager)

• Fixed bug where shrink-wrapping of some content failed on Facebook,

caused by imprecision in LayoutUnit to floating point conversions.

Writing a test for this was tricky as layout tests run without

subpixel text on most platforms. (szager)

Going over the list of OKRs and discussing each one:

[ Have telemetry benchmark suite running key_silk_cases monitoring layout times with less than 1% variation between runs. ]

[ Add 3 real-world pages with lots of layout to key_silk_cases. At least two of which are mobile oriented. ]

<benjhayden> A couple of cases with large variance, most have low variance.

<benjhayden> Layout measurement should fix this in most cases. Some tests have a bi-modal behavior, triggering an extra layout in some cases.

<nduca> We want a link on the layout team site to a set of graphs by the end of the quarter.

<eae> So we're looking pretty good, do we think we can get there by the end of the quarter?

<benjhayden> Yes.

* on track *

[ Speed up some key_silk_cases tests. ]

<eae> We've made a number of small improvements to complex text performance and have ongoing work that should result in a 10% improvement.

<eae> Any other ongoing performance work?

* at risk *

[ Create a Measure API prototype and write-up of lessons learned. ]

<jchaffraix> On second or third prototype, have a better understanding since the Sydney convergence.

<jchaffraix> Github repo with prototype, working on write-up.

* on track *

[ Support natural layout animations (subpixel layout during animation) ]

<eae> No real progress, have rough proof of concept prototype but nothing concrete.

<eae> Might miss.

<nduca> Should be explicit if it wasn't a priority and what we did instead.

* at risk *

[ Finish root layer scrolling. ]

<skobes> Making progress, fixing issues as discovered.

<skobes> Handful of hard problems, some risk of slipping into Q2.

* on track *

[ Move line layout to LayoutUnit. ]

<hartmanng> Distracted by P1 bugs, have made some progress.

<hartmanng> Complications with full-page zoom implementation.

<hartmanng> Should be possible if we get time to work on it.

<szager> Agreed.

* on track *

[ Triage all clusterfuzz asserts and fix 50% of them. [cbiesinger]

<cbiesinger> Starting to realize that 50% might have been a bit optimistic. Not all are reproducible.

<cbiesinger> Without minimized test cases it is really hard, given up on a subset of them (without test cases).

<eae> What would a realistic goal be for Q1?

<cbiesinger> Triaging all reproducible ones and fixing the ones with minimal test cases would be feasible.

* at risk *

[ Have bugs automatically filed for new clusterfuzz asserts. ]

<cbiesinger> Need to work with someone on the clusterfuzz team, should be easy.

* on-track *

[ Render tree modifications during layout. ]

<dsinclair> first-letter is stabilized, list-marker is a lot closer.

<dsinclair> One tricky outstanding issue regarding descendants (list-marker).

<jchaffraix> Full screen is a road block. Re-attach destroys renderer, restarts plugins. Currently we do no reattach. We need to add a hoisting mechanist to make it work. Prototype patch among those lines but it does break plugins. Needs more work and is complicated.

<jchaffraix> Have not had time to dig into it, need to fix path.

<dsinclair> single-item-menu won't be done this quarter.

<dsinclair> On track according to plan, decent amount of risk.

* on track *

High level discussion:

<dsinclair> Renaming rendering to layout has been sucking up a lot of time for everyone.

<eae> As has dealing with regressions and blocking bugs.

<nduca> Are we spending more or less time on work not captured in the OKRs than expected?

<eae> Was expecting about a 50%/50% split between OKR work and high-priority bug fixes. So for this quarter we've spent a bit more time on bugs/regressions than expected.

<nduca> For Q2 OKRs should capture that work.