Re: [PATCH v7 0/8] Patchset enabling hardware based cross-timestamps for next gen Intel platforms

From: Christopher Hall
Date: Mon Feb 22 2016 - 13:34:24 EST


On Thu, 18 Feb 2016 11:26:24 -0800, John Stultz <john.stultz@xxxxxxxxxx> wrote:
On Fri, Feb 12, 2016 at 12:25 PM, Christopher S. Hall
<christopher.s.hall@xxxxxxxxx> wrote:
Modern Intel hardware adds an Always Running Timer (ART) that allows the
network and audio device clocks to precisely cross timestamp the device
clock with the system clock. This allows a precise correlation of the
device time and system time.

Thanks for your continued persistence here Christopher! It is looking
pretty good.

I've queued these up for testing, and if that goes well, and don't hit
anything else in review, I'll likely try to submit all but the last
patch (unless there's an acked-by from the maintainer of that code)
through Thomas for 4.6.

Hi John,

I just sent another patchset (v8). I corrected the comment problems pointed out by Richard Cochran. I also changed the arch/x86 code to use "non-stop" TSC rather than "invariant" TSC. They are *exactly* the same thing (i.e. read from the same bit of the CPUID leaf). The former exists already and should be used instead. Patch 6/8 is the only patch that is changed apart from comments.

Thanks for your help reviewing this.

Chris