[time-nuts] Time stamp degradation being added in javascript

[David J Taylor]

From: David

Possibly not of immediate concern to time-nuts but an article had some
trigger words for them in the initial fixes to the much publicised
problems with Intel/AMD/ARM etc :

"After these changes, the time stamp returned by |performance.now| will
be less precise due to lower resolution. Some browsers are going a step
further and degrade the accuracy by adding a random jitter."

https://hackaday.com/2018/01/06/lowering-javascript-timer-resolution-thwarts-meltdown-and-spectre/

meltdown/spectre background
https://www.theregister.co.uk/2018/01/04/intel_amd_arm_cpu_vulnerability/
================================

David,

This API appears only to affect browsers.

On my Windows systems most have been patched, and I see no visible 
difference on either PPS-synced, LAN-synched or Wi-Fi devices as recorded by 
NTP.  One PC showed an increase in CPU usage, but other PCs performing 
similar tasks have not.  That same PC showed a doubling of jitter from less 
than 2 microseconds to less than 4 microseconds.  It's an i5-4460 Haswell 
processor.

  http://www.satsignal.eu/mrtg/harstad-cpu-week.png

Cheers,
David
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