From: Miroslav Lichvar <mlichvar@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Radim Krcmar <rkrcmar@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Richard Cochran <richardcochran@gmail.com>
Subject: Re: [patch 3/3] PTP: add kvm PTP driver
Date: Wed, 18 Jan 2017 16:54:52 +0100 [thread overview]
Message-ID: <20170118155452.GM14227@localhost> (raw)
In-Reply-To: <20170118142409.GA9713@amt.cnet>
On Wed, Jan 18, 2017 at 12:24:09PM -0200, Marcelo Tosatti wrote:
> On Wed, Jan 18, 2017 at 01:46:58PM +0100, Paolo Bonzini wrote:
> > I'd rather use PTP_SYS_OFFSET_PRECISE instead, but unfortunately chrony
> > does not support it---but I would still prefer you to support
> > PTP_SYS_OFFSET_PRECISE as well.
>
> Sure, I'll check if it makes sense to implement PTP_SYS_OFFSET_PRECISE for
> KVM case.
But is it really so precise that the application can safely assume
there are no errors due to asymmetric delays, etc? I think
PTP_SYS_OFFSET_PRECISE should be supported only if the accuracy of
the offset measured between the HW and system clock is not worse than
the precision of the system clock (typically few tens of nanoseconds).
It would be good to verify the accuracy of the offset when the host
and guest clocks are synchronised to each other over PTP using two
NICs with HW timestamping.
--
Miroslav Lichvar
next prev parent reply other threads:[~2017-01-18 15:55 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-13 12:01 [patch 0/3] KVM virtual PTP driver Marcelo Tosatti
2017-01-13 12:01 ` [patch 1/3] KVM: x86: provide realtime host clock via vsyscall notifiers Marcelo Tosatti
2017-01-13 15:18 ` Radim Krcmar
2017-01-13 15:34 ` Marcelo Tosatti
2017-01-13 16:28 ` Radim Krcmar
2017-01-13 17:51 ` Marcelo Tosatti
2017-01-16 15:40 ` Radim Krcmar
2017-01-13 15:41 ` Konrad Rzeszutek Wilk
2017-01-13 15:46 ` Marcelo Tosatti
2017-01-13 12:01 ` [patch 2/3] KVM: x86: add KVM_HC_CLOCK_OFFSET hypercall Marcelo Tosatti
2017-01-13 15:31 ` Radim Krcmar
2017-01-13 15:43 ` Marcelo Tosatti
2017-01-13 17:07 ` Radim Krcmar
2017-01-13 17:57 ` Marcelo Tosatti
2017-01-13 12:01 ` [patch 3/3] PTP: add kvm PTP driver Marcelo Tosatti
2017-01-13 15:56 ` Radim Krcmar
2017-01-13 17:40 ` Marcelo Tosatti
2017-01-16 16:26 ` Radim Krcmar
2017-01-16 16:54 ` Radim Krcmar
2017-01-16 17:08 ` Marcelo Tosatti
2017-01-16 17:27 ` Radim Krcmar
2017-01-16 17:39 ` Marcelo Tosatti
2017-01-16 18:01 ` Radim Krcmar
2017-01-16 19:36 ` Marcelo Tosatti
2017-01-16 19:47 ` Marcelo Tosatti
2017-01-16 20:01 ` Marcelo Tosatti
2017-01-17 8:03 ` Miroslav Lichvar
2017-01-17 11:30 ` Marcelo Tosatti
2017-01-17 15:36 ` Radim Krcmar
2017-01-18 12:17 ` Marcelo Tosatti
2017-01-18 12:24 ` Marcelo Tosatti
2017-01-18 12:46 ` Paolo Bonzini
2017-01-18 13:36 ` Miroslav Lichvar
2017-01-18 14:02 ` Paolo Bonzini
2017-01-18 14:50 ` Marcelo Tosatti
2017-01-18 15:35 ` Radim Krcmar
2017-01-18 15:45 ` Paolo Bonzini
2017-01-18 15:57 ` Marcelo Tosatti
2017-01-18 14:24 ` Marcelo Tosatti
2017-01-18 15:54 ` Miroslav Lichvar [this message]
2017-01-18 16:07 ` Paolo Bonzini
2017-01-18 16:14 ` Radim Krcmar
2017-01-18 14:37 ` Marcelo Tosatti
2017-01-18 14:53 ` Marcelo Tosatti
2017-01-18 15:20 ` Radim Krcmar
2017-01-18 15:28 ` Marcelo Tosatti
2017-01-20 14:18 ` Radim Krcmar
2017-01-18 15:59 ` Radim Krcmar
2017-01-16 17:04 ` Marcelo Tosatti
2017-01-16 17:46 ` Radim Krcmar
2017-01-16 19:33 ` Marcelo Tosatti
2017-01-14 15:26 ` Richard Cochran
2017-01-16 15:48 ` Radim Krcmar
-- strict thread matches above, loose matches on Subject: below --
2017-01-13 18:45 [patch 0/3] KVM virtual PTP driver (v2) Marcelo Tosatti
2017-01-13 18:46 ` [patch 3/3] PTP: add kvm PTP driver Marcelo Tosatti
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170118155452.GM14227@localhost \
--to=mlichvar@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mtosatti@redhat.com \
--cc=pbonzini@redhat.com \
--cc=richardcochran@gmail.com \
--cc=rkrcmar@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).