On Fri, Feb 08, 2008 at 03:35:04PM +0300, Nikita Zinoviev wrote:
> Do you know if there is a way to get stability attributes
> for registered dtrace probes except
> dtrace -l -v ?
>
> Because as far as I know while registering a usdt provider
> there is a way to set stability attributes (name, data, dependency)
> for provider, module, function, name and arguments of the probe.
>
> Is there any way of getting all of this?
> dtrace -l -v doesn't seem verbose enough..
> For instance, how can I get these attributes for a module or function?
>
> thanks in advance,
>
> Nikita Zinoviev
There is not a direct way of answering the question from the command-line
at present, although the C API to libdtrace does provide the info.
You can, however, sort of fudge your way to the answer like this:
If you run dtrace with -v but *not* -l (which says, expand all my probe
descriptions and list what probes match them) and then add -e to not
bother executing the query, you can get the stability info for the
composition of your probe description. For example, if I want to
know the stability of just provider "fbt" I can do this:
# dtrace -P fbt -e -v
Stability attributes for description fbt:
Minimum Probe Description Attributes
Identifier Names: Unstable
Data Semantics: Unstable
Dependency Class: Common
Minimum Statement Attributes
Identifier Names: Stable
Data Semantics: Stable
Dependency Class: Common
fbt:::
Now suppose I want to know what happens if I were to give fbt a
particular function (i.e. to see what effect composing the function
stability has). I could change the above to this:
# dtrace -n fbt::kmem_alloc:entry -e -v
Stability attributes for description fbt::kmem_alloc:entry:
Minimum Probe Description Attributes
Identifier Names: Private
Data Semantics: Private
Dependency Class: Unknown
Minimum Statement Attributes
Identifier Names: Stable
Data Semantics: Stable
Dependency Class: Common
fbt::kmem_alloc:entry
Probe Description Attributes
Identifier Names: Private
Data Semantics: Private
Dependency Class: Unknown
Argument Attributes
Identifier Names: Private
Data Semantics: Private
Dependency Class: ISA
Argument Types
args[0]: size_t
args[1]: int
Notice how the Probe Description attributes changed from
Unstable/Unstable/Common for fbt::: to Private/Private/Unknown.
So you can see that function names are Private.
That isn't exactly as easy as we could have made it, so I could imagine
an RFE of the form "dtrace -P <provider> -v" should also show the sub-
stability attributes associated with elements of that provider.
-Mike
--
Mike Shapiro, Solaris Kernel Development. blogs.sun.com/mws/
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