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Re: Temporarily reducing precision of DOMHighResTimeStamp in Chrome

From: Ross McIlroy <rmcilroy@google.com>
Date: Mon, 8 Jan 2018 16:26:35 +0000
Message-ID: <CAP-rjT5ppdQejz4ZpX=1tcJrbexHo3J3rGQv3TBR84Nrp2WqDw@mail.gmail.com>
To: Ben Maurer <ben.maurer@gmail.com>
Cc: public-web-perf@w3.org
Yes, the timestamps produced by performance.now() will always be
monotonically increasing.

On 8 January 2018 at 16:15, Ben Maurer <ben.maurer@gmail.com> wrote:

> Will the time stamps be monotonic?
>
> Sent from my iPhone
>
> On Jan 8, 2018, at 4:22 AM, Ross McIlroy <rmcilroy@google.com> wrote:
>
> As part of our mitigations against Speculative Side Channel Attacks
> <https://www.chromium.org/Home/chromium-security/ssca>, Chrome 64 will
> reduce the resolution of DOMHighResTimeStamps to 100us. We are also
> introducing 100us of random jitter to the clock edges to prevent attempts
> to increase resolution via edge-thresholding.  The returned time will be
> within +/100us of real time, however there will be no guarantee as to
> duration (in real time) of clock pulses between these 100us intervals.
>
> We intend for this to be a temporary measure while other mitigation are
> introduced, however we do not have a timeline for restoring the previous
> precision.
>
> Ross / Sami
>
>
Received on Monday, 8 January 2018 16:27:19 UTC

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