[webkit-dev] Suggesting to enable paint timing by default

[Keith Miller]

Results appear to be neutral on the page load time benchmark, so you should be good on that front. I don’t know who the best person to vet the maturity of the code is though, sorry.

Cheers,
Keith

> On Jul 13, 2020, at 11:38 AM, Noam Rosenthal <noam at webkit.org> wrote:
> 
> 
> 
> On Mon, Jul 13, 2020 at 9:15 PM Keith Miller <keith_miller at apple.com <mailto:keith_miller at apple.com>> wrote:
> If you tell me how to enable paint timing by default, I can start an A/B task for you. I’m probably not qualified to review it for code maturity though.
> Awesome, thanks!
> It's an experimental runtime flag calledPaintTimingEnabled
> I have a patch for enabling it by default here: https://bugs.webkit.org/show_bug.cgi?id=211736 <https://bugs.webkit.org/show_bug.cgi?id=211736>
> We mainly need to test that measuring paint timing doesn't (badly) influence loading performance.
> 
>   
> 
> Cheers,
> Keith
> 
>> On Jul 13, 2020, at 3:02 AM, Noam Rosenthal <noam at webkit.org <mailto:noam at webkit.org>> wrote:
>> 
>> 
>> 
>> On Wed, May 27, 2020 at 12:04 PM Yoav Weiss <yoav at yoav.ws <mailto:yoav at yoav.ws>> wrote:
>> +Ryosuke Niwa <mailto:rniwa at webkit.org> +Alex Christensen <mailto:achristensen at apple.com> who were involved in the spec discussions.
>> 
>> On Wed, May 27, 2020 at 10:29 AM Noam Rosenthal <noam at webkit.org <mailto:noam at webkit.org>> wrote:
>> 
>> 
>> Following up on this.
>> FOn Tue, May 12, 2020 at 10:28 AM Maciej Stachowiak <mjs at apple.com <mailto:mjs at apple.com>> wrote:
>> 
>> 
>>> On May 11, 2020, at 9:53 PM, Noam Rosenthal <noam at webkit.org <mailto:noam at webkit.org>> wrote:
>>> 
>>> 
>>> 
>>> On Tue, May 12, 2020 at 1:36 AM Maciej Stachowiak <mjs at apple.com <mailto:mjs at apple.com>> wrote:
>>> 
>>> I noticed from comments in one of the Radars that the patch may result in an additional “fake paint”, so it should probably be performance tested. Have you done any testing? 
>>> I've tested it locally, I haven't noticed any significant side effect, because in complex situations the fake paint only happens once per page and bails early once contentfulness is detected. but I can run any additional test needed.
>>>  
>>> We’ll likely want to A/B some of Apple’s page load speed benchmarks.
>>> A/B testing load speed sounds sensible. How do we go about doing that?
>> 
>> Unfortunately our page load speed benchmarks are not public because they incorporate captured page content, which we can’t freely redistribute.
>> 
>> So, can someone else from Apple review that the code is mature enough for this? Simon had reviewed the original patch. Maybe Zalan/Darin? 
>> 
>> A helpful person from Apple may be able to set up an A/B test for this patch.
>> What's required to ask for help from a helpful person at Apple? :) 
>> Hola
>> Pinging about this again :)
>> The code for paint timing API is sitting there in the repo, waiting either for internal Apple A/B tests, for an additional code maturity review, or for enabling it by default... I'm here if any changes in the code need to be made.
>> 
>> Trying to figure out how we can proceed with this... @Maciej Stachowiak <mailto:mjs at apple.com>?
>> Cheers
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