The confusion may be this: mousemove events are always dispatched at the beginning of a rendering update, that's why it looks like the Composite Layers item is associated with the mousemove event. Click events are dispatched separately from rendering updates. I would guess there are Composite Layers items in the clicking profile, but just not adjacent to the event handlers.
On Fri, Aug 5, 2022, 8:05 PM Maxim Vaarwel <palosh...@gmail.com> wrote: > Stefan Zager, you are a little bit didn't understand me. You wrote: "*if > you're clicking quickly -- let's say 5 times per second -- at 60Hz, that > still means the browser can skip 55 out of a possible 60 rendering updates > per second*". But these 5 clicks don't do Composite Layers unlike > mousemove events. What a sense? > суббота, 6 августа 2022 г. в 07:25:30 UTC+10, Stefan Zager: > >> On Fri, Aug 5, 2022 at 12:41 PM Maxim Vaarwel <palo...@gmail.com> wrote: >> >>> Hello, Stefan Zagar. Could you explain then to me one thing? If >>> dev-tools shows bars named as Composite Layers every time when we use >>> display's hardware. Then why don't I see them when I hold my mouse pointer >>> on one point and do clicks? Also why I don't see Composite Layers bars when >>> I do nothing? That moment need to clarify. >>> >> >> The browser will skip doing rendering updates entirely if nothing is >> happening on the page and it's not receiving input events. Even if you're >> clicking quickly -- let's say 5 times per second -- at 60Hz, that still >> means the browser can skip 55 out of a possible 60 rendering updates per >> second. But when you move the pointer, a mousemove is generated for *every* >> rendering update opportunity, so the browser will keep doing rendering >> updates. >> >> >> >>> >>> P.S Thanks for your respond. >>> >>> суббота, 6 августа 2022 г. в 03:40:07 UTC+10, Stefan Zager: >>> >>>> On Fri, Aug 5, 2022 at 10:05 AM Maxim Vaarwel <palo...@gmail.com> >>>> wrote: >>>> >>>>> Nowadays rendering chrome engine has been changed. >>>>> >>>>> For demonstrating new confusion moment: >>>>> 1. Open a blank tab >>>>> 2. Open dev-tools, next open Perfomance tab and run a recording >>>>> performance >>>>> 3. In process of the recording performance just doing moves by mouse >>>>> on the blank page during 3sec or less (whatever you want) >>>>> 4. Stop the recording performance >>>>> 5. Look at the recorded data. >>>>> 6. Find multiple Composite Layers bars >>>>> >>>>> What does mean Composite Layers now? Why is it invoked by chrome >>>>> render engine if page absolutely clear? >>>>> Why do Update Layers Tree (already it is Pre-Paint) also change? What >>>>> does it actually do? >>>> >>>> >>>> The biggest change since 2019 is that we have completed the >>>> CompositeAfterPaint (CAP). The Life of a Pixel slides refer to CAP; >>>> anything in the slides that says "this will be different when we finish >>>> CAP" is now working the CAP way. >>>> >>>> Every time you move the mouse, we have to figure out whether to >>>> dispatch a mousemove event. To do that, we have to do a hit test to >>>> determine what DOM object is under the mouse pointer. To do that, we have >>>> to make sure the rendering information is up-to-date at least as far as the >>>> Pre-Paint step. That's why you see a sequence of [ Pre-Paint, Hit Test, >>>> Event: mousemove ] in the performance recording. >>>> >>>> If you're using display hardware with a refresh rate of 60Hz, we >>>> attempt to do a full rendering update every 16.7ms. One of the steps of the >>>> rendering update is "see if we should make any changes to the set of >>>> composited layers" -- that is the "Composite Layers" step. Even if the >>>> answer is "no, the current set of composited layers is fine", we will >>>> *still* show that step in the performance data (but it should be very >>>> fast). That is what you're seeing. >>>> >>>> >>>>> пятница, 26 июля 2019 г. в 02:51:34 UTC+10, sko...@chromium.org: >>>>> >>>>>> Hi Prashant, >>>>>> >>>>>> The terminology in devtools timeline items is somewhat misleading. >>>>>> >>>>>> *Update Layer Tree* is currently measuring two things: >>>>>> >>>>>> - Blink compositing update (decides which PaintLayers should be >>>>>> composited, allocates or clears their CompositedLayerMapping, creates and >>>>>> sets geometry and other properties of GraphicsLayers) >>>>>> >>>>>> - prepaint tree walk (issues paint invalidations on the layout >>>>>> objects, and builds paint property trees) >>>>>> >>>>>> *Update Layer* is measuring some of the bookkeeping that occurs in >>>>>> between paint and commit (PictureLayer::Update). I think the main thing >>>>>> this is doing is copying paint ops out of the DrawingDisplayItem (which >>>>>> was >>>>>> created during paint) and into the PictureLayer's RecordingSource (so >>>>>> that >>>>>> the commit can transfer them into the PictureLayerImpl's RasterSource). >>>>>> >>>>>> *Composite Layers* is actually the time that the main thread spends >>>>>> waiting for the commit to finish on the compositor thread. I agree it >>>>>> should instead be named "Commit Layers". >>>>>> >>>>>> At least this is what I have gathered from inspection; others who >>>>>> know more may correct me. >>>>>> >>>>>> Some of this will change with the launch of CompositeAfterPaint. >>>>>> >>>>>> On Tue, 23 Jul 2019 at 22:04, Prashant Palikhe <prash...@gmail.com> >>>>>> wrote: >>>>>> >>>>>>> I am a frontend dev trying to understand the guts of Blink/Chrome in >>>>>>> order to get a grasp on how the code that I write gets converted into >>>>>>> pixels on the screen. >>>>>>> >>>>>>> I have read several Chromium docs like >>>>>>> >>>>>>> >>>>>>> https://www.chromium.org/developers/design-documents/compositor-thread-architecture >>>>>>> >>>>>>> https://chromium.googlesource.com/chromium/src/+/master/docs/how_cc_works.md#raster-and-tile-management >>>>>>> >>>>>>> and watched the brilliant talk by Steve Kobes on Life of a pixel >>>>>>> <https://www.youtube.com/watch?v=w8lm4GV7ahg> >>>>>>> >>>>>>> I am trying to correlate the findings from these sources with the >>>>>>> findings from my own experiments. I have been able to do so for most of >>>>>>> the >>>>>>> things except for >>>>>>> >>>>>>> 1. Update layer >>>>>>> 2. Update layer tree >>>>>>> 3. Composite layers >>>>>>> >>>>>>> These are my understanding so far. And I would like to be either >>>>>>> validated or corrected. >>>>>>> >>>>>>> *Update layer* >>>>>>> >>>>>>> Not really sure what's going on here. Seems like part of painting. >>>>>>> But what does it really mean? >>>>>>> >>>>>>> *Update layer tree* >>>>>>> >>>>>>> To me it seems like this is when the impl side layer tree changes >>>>>>> are applied onto the layer tree on Blink. E.g. after scroll or >>>>>>> pinch/zoom >>>>>>> interactions. >>>>>>> >>>>>>> But if I read Paul's tweet from a while ago, >>>>>>> https://twitter.com/aerotwist/status/498878547378053120?lang=en >>>>>>> >>>>>>> I am not so sure anymore. What is exactly happening here? >>>>>>> >>>>>>> *Composite layers* >>>>>>> >>>>>>> To me this is really confusing since composition is no longer main >>>>>>> thread concept. So why does it even appear in main thread time line. >>>>>>> >>>>>>> To me it seems like this is when the main thread layer tree is >>>>>>> committed to the compositor. This is initiated by the CC with the main >>>>>>> thread blocked. >>>>>>> >>>>>>> If this is true, it seems like "composite layers" is not a right >>>>>>> name. It would make more sense to have "commit layers" e.g. >>>>>>> >>>>>>> But maybe my assumptions are wrong. >>>>>>> >>>>>>> Hope to get clarity on these subjects. >>>>>>> >>>>>>> Thanks >>>>>>> >>>>>>> -- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "blink-dev" group. >>>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>>> send an email to blink-dev+...@chromium.org. >>>>>>> To view this discussion on the web visit >>>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/58b2a915-7a7d-453f-8196-7867cc58892d%40chromium.org >>>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/58b2a915-7a7d-453f-8196-7867cc58892d%40chromium.org?utm_medium=email&utm_source=footer> >>>>>>> . >>>>>>> >>>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "blink-dev" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to blink-dev+...@chromium.org. >>>>> >>>> To view this discussion on the web visit >>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/4349db93-593c-43f8-87ec-374206cc9b1an%40chromium.org >>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/4349db93-593c-43f8-87ec-374206cc9b1an%40chromium.org?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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