DTrace gone quiet?

[Mark Johnston]

On Tue, Apr 16, 2013 at 04:03:06PM -0400, Ryan Stone wrote:
> On Tue, Apr 16, 2013 at 3:57 PM, Navdeep Parhar <np at freebsd.org> wrote:
> 
> > I just upgraded my kernel and userspace to head (r249552) and I notice
> > that DTrace doesn't output anything until I hit ctrl-c.  All previous
> > "hits" on the probe appear lost.  For example:
> >
> > # dtrace -n 'fbt::ether_output:entry'
> > dtrace: description 'fbt::ether_output:entry' matched 1 probe
> >
> > (No output here.  I waited a long time before the ctrl-c and I know the
> > system is actively transmitting and receiving Ethernet traffic).
> >
> > ^C
> > CPU     ID                    FUNCTION:NAME
> >   9  29354               ether_output:entry
> >   8  29354               ether_output:entry
> >   8  29354               ether_output:entry
> >   8  29354               ether_output:entry
> >
> >
> > Can anyone confirm or contradict this on a recent HEAD (around r249552
> > in my case)?
> >
> > Regards,
> > Navdeep
> > _______________________________________________
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> >
> 
> Hm, if you run with "-x bufpolicy=switch" does it work?  It sounds as
> through the ring buffer policy is being set by default for you.  I'm not
> sure how that could happen.

I'm seeing it too as of r249508. Adding those arguments doesn't seem to
have any effect.