Re: [9fans] dtrace for plan 9

[erik quanstrom <quanstro@quanstro.net>]

> DTrace by itself is pretty lame. It needs providers to be interesting.
> By itself, it's a very limited interpreter that supports BEGIN and
> END, and a couple other tiny things (ERROR, maybe?). Devtrace would be
> analogous to the syscall provider for DTrace, from my understanding.

i may be misunderstanding you, but devtrace can trace any
call site or return in the kernel.  not just system calls. and
not just entire functions; one could enable tracing on just
one return, for example.

you just give it a range of addresses and it loops through finding
the magic left by the linker.  enabling a trace atomicly modifies
each site to turn on tracing.

> I'd estimate a finished version to be about the size of
> the Plan 9 kernel.

minooka; wc -l /sys/src/9/*/*trace*.[chs] /sys/src/libc/386/trace.s
    118 /sys/src/9/pc/archtrace.c
     18 /sys/src/9/pc/archtrace.h
    578 /sys/src/9/port/devtrace.c
     33 /sys/src/libc/386/trace.s
    747 total

this stuff's ready to take off.  (har har har.)

- erik