Date: Sat, 29 Nov 2008 19:30:52 +0100 From: "=?ISO-8859-1?Q?Marius_N=FCnnerich?=" <marius@nuenneri.ch> To: "Alexander Leidinger" <Alexander@leidinger.net> Cc: freebsd-current@freebsd.org Subject: Re: HOWTO in wiki: adding custom dtrace probes in the kernel Message-ID: <b649e5e0811291030t7c2bf2f9wff6e61d80b438f27@mail.gmail.com> In-Reply-To: <20081129184431.7a201a3a@deskjail> References: <20081128154514.82247fe47bn83lkw@webmail.leidinger.net> <ggp10c$pdt$1@ger.gmane.org> <20081128172126.453467ea7w6jb5c8@webmail.leidinger.net> <b649e5e0811281047y2401f9adhdb35e3ba8b7aa106@mail.gmail.com> <20081129184431.7a201a3a@deskjail>
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On Sat, Nov 29, 2008 at 6:44 PM, Alexander Leidinger
<Alexander@leidinger.net> wrote:
> Quoting "Marius N=FCnnerich" <marius@nuenneri.ch> (Fri, 28 Nov 2008 19:47=
:21 +0100):
>
>> What is the intention of adding function entry and return providers
>> with SDT? Isn't that what FBT is for?
>
> To make it more easy for the dtrace script writter. If you want to
> trace all linuxulator specific stuff, you can use the wildcard
> linuxulator:::entry { ... }
>
> Or if you want to trace everything specific to linux file related stuff
> you use the wildcard
> linuxulator:file::entry { ... }
>
> With the fbt, this is much more difficult to do. You have to find out
> all related functions and specify them. This may not be hard for a
> kernel developer, but an user with a problem just wants to solve the
> problem, and getting an idea what is going on is more easy with the
> entry and return probes from the sdt, as they have a more narrow
> semantic meaning than the similar probe from the fbt (the fbt just
> tells you it's a kernel function, whereas the linuxulator probe
> provides you with the information that it is a function which belongs
> to the linuxulator and it's corresponding module grouping (like file
> related, ioctl related, ...)). No need to hunt down this info in the
> kernel yourself.
Many thanks for your explanation. That makes sense to me.
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