From: Richard Cochran <richardcochran@gmail.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
devel@linuxdriverproject.org, linux-kernel@vger.kernel.org,
Haiyang Zhang <haiyangz@microsoft.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
John Stultz <john.stultz@linaro.org>,
Alex Ng <alexng@microsoft.com>,
Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH RFC] hv_utils: implement Hyper-V PTP source
Date: Fri, 13 Jan 2017 15:50:48 +0100 [thread overview]
Message-ID: <20170113145048.GA29706@localhost.localdomain> (raw)
In-Reply-To: <20170113130543.7212-1-vkuznets@redhat.com>
On Fri, Jan 13, 2017 at 02:05:43PM +0100, Vitaly Kuznetsov wrote:
> Instead of doing in-kernel time adjustments offload the work to an
> NTP client by exposing TimeSync messages as a PTP device. Users my now
> decide what they want to use as a source.
>
> I tested the solution with chrony, the config was:
>
> refclock PHC /dev/ptp0 poll 3 precision 1e-9
>
> The result I'm seeing is accurate enough, the time delta between the guest
> and the host is almost always within [-10us, +10us], the in-kernel solution
> was giving us comparable results.
This approach is much nicer than the previous one.
> +static int hv_ptp_enable(struct ptp_clock_info *info,
> + struct ptp_clock_request *request, int on)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +static int hv_ptp_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
> +{
> + u64 newtime;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&host_ts.lock, flags);
> + newtime = host_ts.host_time + get_timeadj_latency(host_ts.ref_time);
> + *ts = ns_to_timespec64((newtime - WLTIMEDELTA) * 100);
> + spin_unlock_irqrestore(&host_ts.lock, flags);
> +
> + return 0;
> +}
> +
> +struct ptp_clock_info ptp_hyperv_info = {
> + .name = "hyperv",
> + .enable = hv_ptp_enable,
> + .gettime64 = hv_ptp_gettime,
The code in drivers/ptp/ptp_clock.c calls
.adjfreq (or adjfine)
.adjtime
.settime64
unconditionally, so you need to implement these returning EOPNOTSUPP.
(See also Documentation/ptp/ptp.txt)
> + .owner = THIS_MODULE,
> +};
Thanks,
Richard
next prev parent reply other threads:[~2017-01-13 14:50 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-04 17:24 [PATCH v2 0/4] hv_util: adjust system time smoothly Vitaly Kuznetsov
2017-01-04 17:24 ` [PATCH v2 1/4] timekeeping: export do_adjtimex() to modules Vitaly Kuznetsov
2017-01-07 1:06 ` John Stultz
2017-01-09 13:03 ` Vitaly Kuznetsov
2017-01-04 17:24 ` [PATCH v2 2/4] hv_util: switch to using timespec64 Vitaly Kuznetsov
2017-01-07 1:04 ` John Stultz
2017-01-04 17:24 ` [PATCH v2 3/4] hv_util: use do_adjtimex() to update system time Vitaly Kuznetsov
2017-01-04 19:09 ` Stephen Hemminger
2017-01-05 12:37 ` Vitaly Kuznetsov
2017-01-07 0:56 ` John Stultz
2017-01-04 17:24 ` [PATCH v2 4/4] hv_util: improve time adjustment accuracy by disabling interrupts Vitaly Kuznetsov
2017-01-04 19:17 ` Stephen Hemminger
2017-01-05 12:35 ` Vitaly Kuznetsov
2017-01-05 17:39 ` Stephen Hemminger
2017-01-07 1:02 ` John Stultz
2017-01-09 13:05 ` Vitaly Kuznetsov
2017-01-09 21:27 ` [PATCH v2 0/4] hv_util: adjust system time smoothly Thomas Gleixner
2017-01-10 14:30 ` Vitaly Kuznetsov
2017-01-10 14:58 ` Thomas Gleixner
2017-01-13 13:05 ` [PATCH RFC] hv_utils: implement Hyper-V PTP source Vitaly Kuznetsov
2017-01-13 14:50 ` Richard Cochran [this message]
2017-01-13 15:38 ` Vitaly Kuznetsov
2017-01-13 15:21 ` Olaf Hering
2017-01-13 15:37 ` Vitaly Kuznetsov
2017-01-16 19:29 ` Thomas Gleixner
2017-01-17 9:53 ` Vitaly Kuznetsov
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