[dtrace-discuss] DTrace under Linux

[Casper.Dik at Sun.COM]

>Why do you say that SystemTap only is done on i386?
>Does it means that, compared with DTrace, SystemTap is focused more on
>hardware infomation?

Dynamic kernel probing tools like DTrace need to understand and modify
the instruction streams in the kernel.

>Does DTrace has two different kernel parts?
>I means for the x86 and SPARC architecture, there're something different
>inside the 2 DTraces?

Yes; DTrace is atypical in that it requires quite intimate knowledge
of how instruction streams work.  But from a user's perspective this
is all hidden and you can use the same scripts on both architecture.

The DTrace architecture limits the knowledge of the processor architecture
to the DTrace to the providers which need that knowledge (such as the
fbt and fasttrap provider)

Sun has a requirement for "completeness", i.e., support for all architectures,
when putting a project in Solaris.  That's why we have support for DTrace
on all supported platforms.

In Linux, it is possible that systemtap becomes mainstream without support
for other architectures.  (Systemtap is also much more limited and does not
make the safety guarantees DTrace makes)

Casper