From: Stephen Hemminger <stephen@networkplumber.org>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org, linux-kernel@vger.kernel.org,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Alex Ng <alexng@microsoft.com>
Subject: Re: [PATCH v2 4/4] hv_util: improve time adjustment accuracy by disabling interrupts
Date: Thu, 5 Jan 2017 09:39:13 -0800 [thread overview]
Message-ID: <20170105093913.48d09249@xeon-e3> (raw)
In-Reply-To: <87o9zladld.fsf@vitty.brq.redhat.com>
On Thu, 05 Jan 2017 13:35:58 +0100
Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
> I was thinking about it but to me what do_adjtimex() does looks too
> low-level for drivers (e.g. calling write_seqcount_begin(),
> __timekeeping_set_tai_offset(), tk_update_leap_state()). To me (again, I
> probably know not that much about time keeping) it looks like we'll have
> to have all this stuff around the __do_adjtimex() call here.
>
> Are there any particular concearns on calling do_adjtimex() directly?
With out holding timekeeper_lock, I don't see how you can do the adjtime
atomically. The userspace NTP doesn't worry about it, but in the kernel
you can be more accurate. But to do that you would need to write a new
function that is kernel specific.
next prev parent reply other threads:[~2017-01-05 17:40 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 [this message]
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
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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