Date: Sat, 29 Nov 2008 18:44:31 +0100 From: Alexander Leidinger <Alexander@Leidinger.net> To: "Marius =?UTF-8?B?TsO8bm5lcmljaA==?=" <marius@nuenneri.ch> Cc: freebsd-current@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: HOWTO in wiki: adding custom dtrace probes in the kernel Message-ID: <20081129184431.7a201a3a@deskjail> In-Reply-To: <b649e5e0811281047y2401f9adhdb35e3ba8b7aa106@mail.gmail.com> References: <20081128154514.82247fe47bn83lkw@webmail.leidinger.net> <ggp10c$pdt$1@ger.gmane.org> <20081128172126.453467ea7w6jb5c8@webmail.leidinger.net> <b649e5e0811281047y2401f9adhdb35e3ba8b7aa106@mail.gmail.com>
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Quoting "Marius N=C3=BCnnerich" <marius@nuenneri.ch> (Fri, 28 Nov 2008 19:4=
7:21 +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.
Bye,
Alexander.
--=20
Ferengi Rule of Acquisition #263:
Never let doubt interfere with your lust for latinum.
-- ST:DS9, "Bar Association"
http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID =3D B0063FE7
http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID =3D 72077137
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