In the last episode (Sep 13), Brett Glass said:
> Thank you! Since it's tunable at runtime I just tested it, and -- sure
> enough -- no negative ping times.
>
> Ironically, it was the kernel that selected the ACPI timer, scoring it
> higher than the timestamp counter as a clock source. Perhaps co
[ ...combining two emails... ]
On Sep 13, 2011, at 9:49 AM, Brett Glass wrote:
> If that's indeed the case, the kernel must be doing the math wrong.
While there have undoubtedly have been kernel bugs with timekeeping (and there
may be more still present), it's not uncommon for hardware issues to
At 09:16 AM 9/13/2011, Dan Nelson wrote:
It doesn't roll over in less than a second; it rolls over in 16777215 /
3579545 = 4.6 seconds. Your negative time delta problem isn't due to
rollover.
If that's indeed the case, the kernel must be doing the math wrong.
I wonder how many other systems
Thank you! Since it's tunable at runtime I just tested it, and -- sure enough --
no negative ping times.
Ironically, it was the kernel that selected the ACPI timer, scoring it higher
than the timestamp counter as a clock source. Perhaps code should be added to
ensure that the timer is not chosen
On Mon, Sep 12, 2011 at 10:30 PM, Brett Glass wrote:
> At 06:15 PM 9/12/2011, Chuck Swiger wrote:
>
> > sysctl -a kern.timecounter
>
> No docs on how to do this. Is this done by, for example, setting
>
> kern.timecounter.hardware="TSC"
>
> in loader.conf?
>
it's a runtime tunable so /etc/sysctl
At 06:54 PM 9/12/2011, b. f. wrote:
If you are just upgrading now, why not use 9 BETA?
Production machine.
Also, whenever we create a new production box, we normally pick the
release (not beta; we need to be able to do binary upgrades and
this is only supported from one release to another) wi
At 06:15 PM 9/12/2011, Chuck Swiger wrote:
>Your system's timekeeping appears to be busted. Are you running ntpd with
>"tinker step 0.0" or some home-grown mechanism which might be forcibly
>stepping the clock rather than skewing it, by any chance?
Nothing like that.
>Anyway, the output of:
> I just put FreeBSD 8.1 up on an old (but good) 500 MHz Celeron with
> half a gig of RAM. Interfaces are classic xl (3Com) and dc (DEC
> tulip). Works quite nicely except for one quirk: ping times that
> ought to be positive (no more than 200 ms worst case) are coming
> out negative! Can't figure
On Sep 12, 2011, at 4:50 PM, Brett Glass wrote:
> What's more, it appears that the negative ping times being shown for pings of
> localhost are off by about -687 ms, consistently. Any ideas?
Your system's timekeeping appears to be busted. Are you running ntpd with
"tinker step 0.0" or some home-
More information regarding the odd behavior I'm seeing. Turns out
that packets do not even need to leave the machine for it to
report large negative ping times, on the order of more than half
a second. (See below.) Clearly something is odd about timekeeping
in this system (SiS motherboard chipset,
Here's a puzzler.
I just put FreeBSD 8.1 up on an old (but good) 500 MHz Celeron with
half a gig of RAM. Interfaces are classic xl (3Com) and dc (DEC
tulip). Works quite nicely except for one quirk: ping times that
ought to be positive (no more than 200 ms worst case) are coming
out negative!
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