Date: Wed, 11 Oct 2017 11:49:01 +0200 From: Sebastian Huber <sebastian.huber@embedded-brains.de> To: Konstantin Belousov <kostikbel@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: [PATCH] Simplify th_bintime update in tc_windup() Message-ID: <94f238ec-4cac-7c27-87ac-bc84d13d2eda@embedded-brains.de> In-Reply-To: <20171011093101.GX95911@kib.kiev.ua> References: <20171011064816.20809-1-sebastian.huber@embedded-brains.de> <20171011093101.GX95911@kib.kiev.ua>
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On 11/10/17 11:31, Konstantin Belousov wrote:
> On Wed, Oct 11, 2017 at 08:48:16AM +0200, Sebastian Huber wrote:
>> The th_bintime, th_microtime and th_nanotime members of the timehand a=
ll
>> cache the last system time (uptime + boottime). Only the format
>> differs. Do not re-calculate the bintime and simply use the value use=
d
>> to calculate the microtime and nanotime.
>>
>> Group all the updates under the relevant comment.
> th->th_bintime is recalculated after possible adjustments made by
> the ntp loop to the th_boottime.
The loop is:
=C2=A0=C2=A0=C2=A0 bt =3D th->th_offset;
=C2=A0=C2=A0=C2=A0 bintime_add(&bt, &th->th_boottime);
<--- here the bt is our new system time
=C2=A0=C2=A0=C2=A0 i =3D bt.sec - tho->th_microtime.tv_sec;
=C2=A0=C2=A0=C2=A0 if (i > LARGE_STEP)
=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 i =3D 2;
=C2=A0=C2=A0=C2=A0 for (; i > 0; i--) {
=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 t =3D bt.sec;
=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 ntp_update_second(&th->th_adjustme=
nt, &bt.sec);
=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 if (bt.sec !=3D t)
<-- here the bt.sec changed
=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 th->th_boottime=
.sec +=3D bt.sec - t;
<-- here we update the boottime seconds, so now bt =3D=3D uptime + bootti=
me
=C2=A0=C2=A0=C2=A0 }
So, I think the patch is correct.
>
> But your patch makes me consider the two lines after the XXX comment.
> Shouldn't we use the updated th_bintime instead of the pre-adjustment
> bt value ?
>
All values should reflect the same time.
--=20
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.huber@embedded-brains.de
PGP : Public key available on request.
Diese Nachricht ist keine gesch=C3=A4ftliche Mitteilung im Sinne des EHUG=
.
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