Re: User Timing Mark Name for "Critical Content Loaded"?

On 06/24/2015 05:06 PM, Jonas Sicking wrote:
> I still think that the bigger question isn't what string value to use,
> but whether it is appropriate to say that certain "mark" names have
> semantic meaning or not.
>
> The way that the spec currently works, from my understanding, is that
> it says "you can use whatever name of a mark you want. The names have
> whatever meaning you assign to them. Except if you use names X, Y or
> Z, those have a very specific meaning and will cause A, B and C to
> happen.".

I actually don't believe the spec says that it will cause anything 
besides recording the time of the mark. They were more intended to help 
web performance analytics [1] [2]. As such, the developers have been 
encouraged to use them but we made it clear that the user agent does not 
validate that the usage of those marks is correct.

> Another way to put this is that it feels weird that we have an API
> which allows a page to add page-defined marker to a timeline. Except
> that if you give those marker a specific name, it affects when the UA
> render the page, which is a functionality completely unrelated to the
> timeline (other than that both functionalities involve "time").

It shouldn't affect the UA. If it did, this went beyond the original intent.

Imho, we should ask ourselves if those marks have been useful for 
analytics. It seems that the answer from Firefox OS is "no thanks, we 
made our own".

It would be useful to have some measures of usage out there of those 
marks and also get a picture of which analytic tool, if any, is actually 
using them (or if they recommend a different set as well).

Based on that, we could either keep what we have, drop it, or recommend 
a new set of marks for analytics. If we want to go beyond that, ie 
actually provide hints for user agents, that would be a new direction imho.

Philippe

[1] https://lists.w3.org/Archives/Public/public-web-perf/2011Jan/0038.html
[2] https://lists.w3.org/Archives/Public/public-web-perf/2011Mar/0003.html

Received on Wednesday, 24 June 2015 21:32:52 UTC