Re: communicating server timing data to the client.. Server Timing?

On Wed, Nov 12, 2014 at 7:10 AM, Eli Perelman <eperelman@mozilla.com> wrote:

> I really like this proposal, but I do find keeping the values as durations
> to be somewhat limiting. Just as we have performance marks and measures, I
> feel that being able to provide both durations and timestamps to the client
> would be useful.
>
> A specific use case: On Firefox OS, it would be valuable to specify in
> this header when the user initiated to open an application. The "home
> screen" (acting as the server in this proposal) could specify in the header
> that at a certain timestamp, the user tapped on an icon, and the
> application (acting as the client) would then be able to make a more
> deterministic evaluation for how long it actually took load. Drawback: not
> sure of the implications of introducing timestamps or possible negative
> values into the timeline of an application, but that is something we could
> discuss.
>
> Thoughts?


The problem is that server and client have completely different clocks..
- they're not synchronized, nor can we expect or make them be synchronized
- client uses hr-time and its timestamps are with respect to navigationStart

We can't meaningfully map server generated timestamps into the timeline, I
think we should stick to duration only.

ig