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Re: Updates to Navigation Timing errata

From: Philippe Le Hegaret <plh@w3.org>
Date: Tue, 14 May 2013 18:22:40 -0400
Message-ID: <1368570160.2099.53.camel@chacal>
To: "McCall, Mike" <mmccall@akamai.com>
Cc: Arvind Jain <arvind@google.com>, Boris Zbarsky <bzbarsky@mit.edu>, public-web-perf <public-web-perf@w3.org>
On Tue, 2013-05-14 at 12:36 -0500, McCall, Mike wrote:
> Having a
> domainLookupStart/End == fetchStart in a pre-resolve makes it useless as a
> metric as browsers become more aggressive about pre-resolving hostnames.

The problem here is that navigation timing, like others, defines time as
"For all navigations, including subdocument navigations, the user agent
must record the system clock at the beginning of the root document
navigation and define subsequent timing attributes in terms of a
monotonic clock measuring time elapsed from the beginning of the
navigation."

And since the difference isn't allowed to be negative, having
domainLookupStart inferior to ftechStart could break the monotonic clock
constraint.

Philippe
Received on Tuesday, 14 May 2013 22:22:50 UTC

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