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<div class="moz-cite-prefix">On 6/29/20 11:14 AM, Howard F.
Cunningham wrote:<br>
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<p><snip/><br>
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<p><b><i><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">[HC:>]
When you say clock jitter I think that you are saying
that the clock drifts, probably slower, over time. This
tells me that the system is busy and missing the clock
timings. When Windows starts, it checks the BIOS clock
for its time. While running Windows does not check the
BIOS clock but rather updates a counter which is used
for the time. I wonder if telling Windows to use a ntp
server would solve this problem.</span></i></b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
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<p>Not in this case -- the clock itself is fine and doesn't drift;
at least not enough to be seen on screen.</p>
<p>The clock jitter I'm talking about is fine-grained and has to do
with missing samples in the data stream. It appears to be a
scheduling problem.</p>
<p>This even occurs if the CPUs allocated in the VM are given
"realtime" priority; and doesn't seem to depend on load because
the VM is significantly over-provisioned.<br>
</p>
<snip/><br>
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<p><b><i><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">[HC:>]
I never said that Windows was more stable than Linux.</span></i></b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
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<p>No, you didn't, and I did not mean to imply that, sorry.<br>
</p>
<snip/><br>
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<p><b><i><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">[HC:>]
My clients do not routinely reboot their computers.
What usually happens is that the systems are rebooted as
part of the monthly patch process. That most likely
prevents us from seeing the need to reboot random
Windows 10.</span></i></b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
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<p>I suspect that they are not running applications that require
long-running critical timing tasks<br>
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<p><br>
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<p>Trying to support long-running timing critical software on
Windows is problematic and requires special care -- that's all
I'm saying. I didn't make it up.<o:p></o:p></p>
<p><b><i><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">[HC:>]
I never said that Windows never needs rebooting and I
did not say that there are never problems on some
Windows systems. The problem has very muchly improved
today. What I should have said is that Windows should
not need to be rebooted daily or even weekly. Where we
see this problem we are able to track the need to reboot
down to a specific program that causing the problem.</span></i></b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
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<p>That seems reasonable in some cases; but often enough for my
experiences that's not a viable approach -- I know there is a
give-and-take in play here that may not match up.<br>
</p>
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style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> A
thought on the unlimited amount of data.. You could try
running a scheduled task to delete the data. Keep in mind
that I do not know if this data is needed or what happens
if the data is deleted while wispr is running. If wispr
needs that data while running, you could try using a
scheduled task to shutdown wispr, delete the files, and
restart wispr (assuming that wispr does not require any
keyboard interaction to start)</span><o:p></o:p></p>
</blockquote>
<p>I don't think it's required by wspr -- wspr is simply
generating the data as some kind of log... given the
unmitigatable bloat of win* 40G of disk space is not enough
after a few days and wspr will generate enough data to fill up
the remaining space; but since I have to reboot it in order to
avoid the timing problems it's a) not a problem to delete the
data (there is indeed a menu option for it in the program) and
b) a scheduled task would not run reliably because of the
necessary reboot.<o:p></o:p></p>
<p><b><i><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">[HC:>]
We use a tool that allows to schedule things like
deleting files like this. We have also used it to reset
the clock on a couple of systems that has clock drift.
That was years ago.</span></i></b></p>
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<p>Clock drift is not a problem in this case, but rather clock
jitter and scheduling jitter. As for deleting the files -- I could
probably schedule something; but as I pointed out it's more
straight forward to simply use the wspr software to delete the
files (rather than reverse engineering where they live and being
concerned with whether wspr knows I've deleted them).<br>
</p>
<p><br>
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<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p>It's not as terrible as it seems -- one should check in on
these kinds of systems periodically as a matter of course
anyway; so handling the required reboot and reset as part of
that maintenance is easy enough to fit in.<o:p></o:p></p>
<p><b><i><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">[HC:>]
We do monitor all of our client systems to hopefully
catch problems before the client sees them.</span></i></b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
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<p>I know you do :-)</p>
<p>I'm not trying to pick a fight -- just reporting real-world
experiences and the mitigations I'm using in response.</p>
<p>There are other ways to slice this too -- as was pointed out: I
_could_ run the whole thing on dedicated hardware and might get
different results -- BUT that's costly, complex, and inefficient
for other reasons. I have plenty of hardware already and
virtualizing things makes it easy to manage and maintain. It's
important that things work well in a fluid virtualized environment
as that is the direction computing is going.</p>
<p>Everything else I'm doing works in this environment; I shouldn't
have to dedicate hardware to every specific case -- especially
when the performance requirements are not that significant (wspr
is not a high bandwidth operation).</p>
<p>I may be pushing the envelope a bit (I tend to do that) but in
this case not really ... it should "just work" and it doesn't ...
So I'm pointing out where the edges are.<br>
</p>
<p>Best,</p>
<p>_M</p>
<p><br>
</p>
<p><br>
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<p>_M<o:p></o:p></p>
<p><o:p> </o:p></p>
<pre>-- <o:p></o:p></pre>
<pre>kf4hcw<o:p></o:p></pre>
<pre>Pete McNeil<o:p></o:p></pre>
<pre>lifeatwarp9.com/kf4hcw<o:p></o:p></pre>
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<p><br>
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<pre class="moz-signature" cols="72">--
kf4hcw
Pete McNeil
lifeatwarp9.com/kf4hcw</pre>
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