Re: [RFT] llquantize for FreeBSD's dtrace

Pedro Giffuni <pfg_at_freebsd.org> wrote:

> Hello Fabian;
> 
> --- Sab 23/6/12, Fabian Keil ha scritto:
> 
> > Pedro Giffuni <pfg_at_FreeBSD.org> wrote:
> > 
> > > I am not a Dtrace user (yet) but I started to port the
> > Log/linear
> > > quantizations from Illumos:
> > > 
> > > http://dtrace.org/blogs/bmc/2011/02/08/llquantize/
> > > 
> > > Apparently this patch should do it:
> > > 
> > > http://people.freebsd.org/~pfg/patches/patch-llquantize-complete
> > > 
> > > Unfortunately when I tried to build current with Dtrace
> > > support, my i386 Virtualbox VM got stuck in ctfmerge so
> > > this is completely untested.
> > > 
> > > Testers that know how to use it are welcome :).
> > 
> > I applied it on 10-CURRENT amd64 from /usr/src with patch
> > -p0 without any conflicts, but it doesn't appear to be
> > working.
> > 
> > The example from the blog post above triggers an assertion
> > that is still reproducible when reducing the test case:
> > 
> > fk_at_r500 /tmp $sudo dtrace -n 'tick-1ms{_at_ = llquantize(i++,
> > 10, 0, 6, 20);}'
> > Assertion failed: (!(arg & (UINT16_MAX <<
> > args[i].shift))), file
> > /usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_cc.c,
> > line 1429.
> >
> 
> Thanks for testing!
> 
> It seems like the syntax has changed from the time the
> example from the blog was made. The code says:
> 
> /*
>  * For log/linear quantizations, we have between one and five
>  * arguments in addition to the expression:
>  *
>  *    arg1 => Factor
>  *    arg2 => Low magnitude
>  *    arg3 => High magnitude
>  *    arg4 => Number of steps per magnitude
>  *    arg5 => Quantization increment value (defaults to 1)
>  */
> 
> 
> My suggestion would be to instead try using the test
> scripts in
> cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/llquantize/
> 
> err.D_LLQUANT_FACTORSMALL.d (for example) has
> 
> _at_ = llquantize(0, 1, 0, 10, 10);

The problem appears to be unrelated to the syntax change:

fk_at_r500 /usr/src/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/llquantize $sudo dtrace -s err.D_LLQUANT_FACTORSMALL.d
Assertion failed: (!(arg & (UINT16_MAX << args[i].shift))), file /usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_cc.c, line 1429.
fk_at_r500 /usr/src/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/llquantize $sudo dtrace -s tst.bases.d
Assertion failed: (!(arg & (UINT16_MAX << args[i].shift))), file /usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_cc.c, line 1429.
fk_at_r500 /usr/src/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/llquantize $sudo dtrace -s tst.negvalue.d
Assertion failed: (!(arg & (UINT16_MAX << args[i].shift))), file /usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_cc.c, line 1429.
fk_at_r500 /usr/src/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/llquantize $sudo dtrace -s tst.steps.d
Assertion failed: (!(arg & (UINT16_MAX << args[i].shift))), file /usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_cc.c, line 1429.

root_at_r500:/root # dtrace -s /usr/src/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/llquantize/tst.steps.d
Assertion failed: (!(arg & (UINT16_MAX << args[i].shift))), file /usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_cc.c, line 1429.
Abort (core dumped)

Fabian