From: Miroslav Lichvar <mlichvar@redhat.com>
To: Richard Cochran <richardcochran@gmail.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>,
Radim Krcmar <rkrcmar@redhat.com>
Subject: Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross timestamps infrastructure
Date: Tue, 24 Jan 2017 09:15:56 +0100 [thread overview]
Message-ID: <20170124081556.GY14227@localhost> (raw)
In-Reply-To: <20170124053243.GA1906@localhost.localdomain>
On Tue, Jan 24, 2017 at 06:32:43AM +0100, Richard Cochran wrote:
> On Mon, Jan 23, 2017 at 09:06:20PM -0200, Marcelo Tosatti wrote:
> > Can you please describe what problem exists with this scheme?
>
> This new kernel code exists just because chrony doesn't implement the
> PRECISE ioctl. Instead of adding new "fake" modes, just teach chrony
> about the better method.
The latest development code of chrony now supports the PRECISE ioctl.
I did some tests with an e1000e NIC (i219) and it seemed the stability
was slightly worse than with the non-PRECISE ioctl, but there was a
400-500ns offset between the two, so it should be much more accurate
(we finally have something that avoids the asymmetry on the PCI-e
bus?). Configuring the refclock with a shorter dpoll should compensate
for the decrease in stability. In any case, there is a "nocrossts"
option to not use the PRECISE ioctl even if it's supported.
--
Miroslav Lichvar
next prev parent reply other threads:[~2017-01-24 8:15 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-20 12:20 [patch 0/5] KVM virtual PTP driver (v3) Marcelo Tosatti
2017-01-20 12:20 ` [patch 1/5] KVM: x86: provide realtime host clock via vsyscall notifiers Marcelo Tosatti
2017-01-20 12:20 ` [patch 2/5] KVM: x86: add KVM_HC_CLOCK_OFFSET hypercall Marcelo Tosatti
2017-01-20 12:20 ` [patch 3/5] kvmclock: export kvmclock clocksource pointer Marcelo Tosatti
2017-01-20 12:55 ` Paolo Bonzini
2017-01-20 12:20 ` [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross timestamps infrastructure Marcelo Tosatti
2017-01-20 12:55 ` Paolo Bonzini
2017-01-20 13:07 ` Marcelo Tosatti
2017-01-20 13:36 ` Paolo Bonzini
2017-01-20 13:52 ` Marcelo Tosatti
2017-01-20 14:02 ` Radim Krcmar
2017-01-20 14:23 ` Paolo Bonzini
2017-01-20 14:31 ` Miroslav Lichvar
2017-01-20 18:30 ` Radim Krcmar
2017-01-20 20:25 ` Richard Cochran
2017-01-23 13:19 ` Marcelo Tosatti
2017-01-23 18:44 ` Richard Cochran
2017-01-23 19:44 ` Paolo Bonzini
2017-01-24 5:43 ` Richard Cochran
2017-01-24 11:23 ` Marcelo Tosatti
2017-01-24 11:35 ` Richard Cochran
2017-01-23 23:06 ` Marcelo Tosatti
2017-01-24 5:32 ` Richard Cochran
2017-01-24 8:15 ` Miroslav Lichvar [this message]
2017-01-20 12:20 ` [patch 5/5] PTP: add kvm PTP driver Marcelo Tosatti
2017-01-20 12:58 ` Paolo Bonzini
2017-01-20 13:11 ` Marcelo Tosatti
2017-01-20 14:12 ` Radim Krcmar
2017-01-20 14:20 ` Radim Krcmar
2017-01-20 15:00 ` Marcelo Tosatti
2017-01-20 17:11 ` Paolo Bonzini
2017-01-20 18:08 ` Radim Krcmar
2017-01-20 19:10 ` Marcelo Tosatti
2017-01-21 8:02 ` Paolo Bonzini
2017-01-20 13:10 ` [patch 0/5] KVM virtual PTP driver (v3) Paolo Bonzini
-- strict thread matches above, loose matches on Subject: below --
2017-01-20 14:51 [patch 0/5] KVM virtual PTP driver (v4) Marcelo Tosatti
2017-01-20 14:51 ` [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross timestamps infrastructure 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=20170124081556.GY14227@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.