| Re: [chrony-users] Hardware timestamping in CentOS 7.4 (was: Possible to get sub-millisecond accuracy?) |
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- To: chrony-users@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-users] Hardware timestamping in CentOS 7.4 (was: Possible to get sub-millisecond accuracy?)
- From: Chris Perl <cperl@xxxxxxxxxxxxxx>
- Date: Fri, 23 Jun 2017 12:11:36 -0400
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On Fri, Jun 23, 2017 at 11:57 AM, Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
> That's an interesting idea. Do you think people would prefer SW RX+HW
> TX timestamping over SW RX+SW TX?
"SW" in this context means kernel timestamps, right?
When I sent that email I was thinking it would be nice. But, now I'm not sure.
On the one hand, moving toward the hardware removes variance from the
measurements. But, on the other, you're essentially ensuring that
you've introduced some asymmetry to the calculation (unless you have
the other side configured the same way). So, I suppose it could be
useful, if you're careful.
Is it the case that the kernel changes that are coming with 7.4 are
going to allow me to use kernel timestamps for both rx and tx? Right
now all my chrony instances on 7.3 are using kernel timestamps for tx
and daemon timestamps for tx.
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