[webkit-dev] PSA: higher precision event timestamp landing soon - port verification needed

Rick Byers rbyers at chromium.org
Mon Jun 10 17:25:57 PDT 2013

On Mon, Jun 10, 2013 at 5:19 PM, Benjamin Poulain <benjamin at webkit.org>wrote:

> On Mon, Jun 10, 2013 at 7:37 AM, Rick Byers <rbyers at chromium.org> wrote:
>> There's been discussion / patches in the past for exposing system time as
>> a separate timestamp on the Event object (as IE does).  See
>> https://lists.webkit.org/pipermail/webkit-dev/2012-October/022574.html,
>> https://bugs.webkit.org/show_bug.cgi?id=94987 and
>> http://lists.w3.org/Archives/Public/public-web-perf/2012Oct/0046.html.
>> In particular, the use of UNIX-epoch timestamps means such measurements
>> will never be completely accurate (due to NTP skew, leap seconds, etc.).
>>  But just updating the timestamp everyone uses to be more accurate (even if
>> not perfect) seems like a clear win.
>> Do you think both approaches should be pursued, or is updating the
>> existing timestamp to be as accurate as possible within the epoch semantics
>> good enough?
>  Kind of different goals in one timestamp. :)
> For input events, the accurate time delta covers many use cases. High
> precision time would be nice but it is not really a must have.

Right, but isn't NTP skew a problem (at least in theory) even for accurate
time deltas when using an epoch-based timestamp?  At least I believe that's
part of the push back flackr@ got when he tried to plumb PlatformEvent
timestamps into the DOM event objects a few months back.

> For other kind of events, a high precision timestamp like you suggest
> could make sense.

> Benjamin
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