noob q.: trying to trace syscalls in Jessie... why do I get unselected "events" in the trace?

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Dear everyone,

I'm trying to trace some syscalls in Debian Jessie, 
that's the distro kernel 3.16.0-4-amd64 .
My motivation is to trace manipulations / forced adjustments of the 
system timebase: ntpd, ntpdate, date -s  or some such.

I've figured out most of the stuff already, I guess. 
The lines are too long for an e-mail body - I'm attaching a sample of 
what I'm doing, in a file called "tracing.txt" (UNIX EOLs).

What strikes me: even if I enable just six individual "events", in 
the trace buffer (output) I get a waterfall of unrelated events being 
logged - looks like routine process scheduler clockwork.
See the attached havoc.txt.
Is it fruitful to capture those events in the first place, only to 
have to filter most of it away?
I haven't found a way to prevent actual tracing of those events, I 
can only filter them from being logged (which sounds like a second 
stage after capturing).

Filtering the trace output works in the sense that I only get
the interesting syscalls in my trace, but actually capturing all the 
process scheduler fuss in the background feels like a lot of 
unnecessary CPU load, which might be a problem on a busy machine, or 
on a machine trying to do its best at timekeeping...

Is this a "feature" of this relatively old debianese kernel?
Is there a way to prevent capturing the scheduler events,
by way of some simple configuration?
I haven't tried a newer or vanilla kernel... does it still work the 
same way in more modern kernels?

BTW, marvellous job on the tracing infrastructure... kudos.
This is like strace on steroids.
Actually I've just used strace to find out what syscalls I should be 
watching in the kernel in the first place :-)
Any ideas are welcome, and have a nice day everybody :-)

Frank Rysanek
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   ---- File information -----------
     File:  havoc.txt
     Date:  27 Apr 2017, 0:39
     Size:  3742 bytes.
     Type:  Text

Attachment: havoc.txt
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     File:  tracing.txt
     Date:  27 Apr 2017, 0:41
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