✘sys_fuzz * ntp_random()

[Gary E. Miller]

Yo All!

To follow up on my own mistake...

On Wed, 25 Jan 2017 16:52:58 -0800
"Gary E. Miller" <gem at rellim.com> wrote:

> Xeon:	 	fuzz=0.000202, tick=0.000202
> skylake:	fuzz=0.000109, tick=0.000109
> RasPi:	fuzz=0.003,    tick=0.003
> RasPi2:	fuzz=0.001823, tick=0.001823
> RasPi3:	fuzz=0.000937, tick=0.000937
> mac mini:     fuzz=0.0005,   tick=0.001

My eye slipped. sys_tick is greater than sys_fuzz.

> Anyone got the reverse case?

Does anyone ever see sys_fuzz > sys_tick?

Hmm, measure_tick_fuzz() in ntpd/ntp_proto.c ensures sys_fuzz <= sys_tick.

So that is answered.  Can't happen.

systime.c has this odd code:

        if (sys_tick > sys_fuzz)
                quant = sys_tick;
        else
                quant = 1e-6;

Not sure why that last line is not quant = sys_fuzz.  I distrust
magic constants.  Not sure it even matters.  Prolly for legacy
adjtime() that only support micro Seconds?  Not gonna worry about it
if it is just old Macs.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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