On Fri, Aug 5, 2022 at 12:41 PM Maxim Vaarwel <palosh...@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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