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

[Noam Rosenthal]

On Mon, Jul 13, 2020 at 9:15 PM Keith Miller <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
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> wrote:
>
>
>
> On Wed, May 27, 2020 at 12:04 PM Yoav Weiss <yoav at yoav.ws> wrote:
>
>> +Ryosuke Niwa <rniwa at webkit.org> +Alex Christensen
>> <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> wrote:
>>
>>>
>>>
>>> Following up on this.
>>>
>>>> FOn Tue, May 12, 2020 at 10:28 AM Maciej Stachowiak <mjs at apple.com>
>>>> wrote:
>>>>
>>>>>
>>>>>
>>>>> On May 11, 2020, at 9:53 PM, Noam Rosenthal <noam at webkit.org> wrote:
>>>>>
>>>>>
>>>>>
>>>>> On Tue, May 12, 2020 at 1:36 AM Maciej Stachowiak <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
> <mjs at apple.com>?
> Cheers
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>
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