[dev-servo] Partial layout flushes
Has there been any thought put into being able to satisfy queries for layout information without doing a full style + layout flush on the page? There are obviously things like CSS containment that can help here, but it seems like it might be worth it to see whether we can detect situations in which whatever stuff is dirty can't affect the information being queried. Yes, I know this is a hard, researchy, problem. ;) -Boris ___ dev-servo mailing list dev-servo@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-servo
Re: [dev-servo] Partial layout flushes
Responses to layout queries are just sent messages (if layout needed invoking to answer them). It is possible to send them early as soon as the relevant data has been computed. Servo does not do this currently though. An initial implementation could just reply with the answer and then keep running layout to completion. I assume this will still require styling + 2 tree passes in most cases, but the last pass will be shortened. jack. On Mon, Mar 27, 2017 at 8:28 AM, Boris Zbarsky wrote: > Has there been any thought put into being able to satisfy queries for layout > information without doing a full style + layout flush on the page? There > are obviously things like CSS containment that can help here, but it seems > like it might be worth it to see whether we can detect situations in which > whatever stuff is dirty can't affect the information being queried. > > Yes, I know this is a hard, researchy, problem. ;) > > -Boris > ___ > dev-servo mailing list > dev-servo@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-servo ___ dev-servo mailing list dev-servo@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-servo
Re: [dev-servo] Partial layout flushes
On 3/27/17 10:36 AM, Jack Moffitt wrote: Responses to layout queries are just sent messages (if layout needed invoking to answer them). It is possible to send them early as soon as the relevant data has been computed. Servo does not do this currently though. An initial implementation could just reply with the answer and then keep running layout to completion. I assume this will still require styling + 2 tree passes in most cases, but the last pass will be shortened. That would be an interesting start, yes. How would it handle the common failure mode I'd really like to address, where a page does: 1) Modify style. 2) Ask for layout data. 3) Modify style. 4) Ask for layout data. At step 4, will we just need to wait for the layout from step 2 to complete before we can start the new restyling pass? -Boris ___ dev-servo mailing list dev-servo@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-servo
Re: [dev-servo] Partial layout flushes
> How would it handle the common failure mode I'd really like to address, > where a page does: > > 1) Modify style. > 2) Ask for layout data. > 3) Modify style. > 4) Ask for layout data. > > At step 4, will we just need to wait for the layout from step 2 to complete > before we can start the new restyling pass? Yes, but since layout runs in parallel and is pretty fast, I'd think the common case was that it would be done by the time it got the second request. I would think it would not be all that much harder to actually stop layout before it was complete too, so this case would be handled, but that leaves you with changes to the tree which haven't produced display lists. My guess is that it will be hard to know whether another synchronous query is coming and which mode should be engaged. jack. ___ dev-servo mailing list dev-servo@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-servo
Re: [dev-servo] Partial layout flushes
On 3/27/17 12:05 PM, Jack Moffitt wrote: Yes, but since layout runs in parallel and is pretty fast, I'd think the common case was that it would be done by the time it got the second request. I doubt layout is "pretty fast" on the scale involved here, which is "hundreds of times per frame". But I'm obviously willing to be convinced otherwise by measurements. ;) My guess is that it will be hard to know whether another synchronous query is coming and which mode should be engaged. Yes, I'm not saying there are easy solutions here. -Boris ___ dev-servo mailing list dev-servo@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-servo
