fche changed the topic of #systemtap to: http://sourceware.org/systemtap; email systemtap@sourceware.org if answers here not timely, conversations may be logged
wcohen has quit [Remote host closed the connection]
pwithnall_ has joined #systemtap
hpt has joined #systemtap
pwithnall_ has quit [Quit: pwithnall_]
wcohen has joined #systemtap
ananth has joined #systemtap
ananth has quit [Quit: Leaving]
ananth has joined #systemtap
ravi_ has joined #systemtap
toothe has joined #systemtap
<toothe>
hi all!
<toothe>
JUST learned about systemtap, interested in using it...
hkshaw has joined #systemtap
<toothe>
I am going through the systemtap documentation.
<toothe>
I know what I want to do, but not quite sure how to do it.
<toothe>
I want to see every function call done inside of this function: module("rtl_pci").function("rtl_pci_probe@/build/linux-W6HB68/linux-4.4.0/drivers/net/wireless/realtek/rtlwifi/pci.c:2172")
<toothe>
by "every" maybe 4 deep
Humble has quit [Ping timeout: 246 seconds]
<toothe>
oh, probefunc()
<toothe>
okay - second problem. Why are some function calls blacklisted?
<toothe>
okay awesome - so I have my stp script begin/end properly. Within the probe I setup, is there a way to monitor what is happening within the function of choice?
hpt has quit [Quit: Lost terminal]
Humble has joined #systemtap
ananth has quit [Ping timeout: 240 seconds]
pwithnall__ has joined #systemtap
scox has quit [Ping timeout: 260 seconds]
mjw has joined #systemtap
hkshaw has quit [Ping timeout: 240 seconds]
hkshaw has joined #systemtap
ravi_ has quit [Ping timeout: 264 seconds]
DuncanT has joined #systemtap
wcohen has quit [Ping timeout: 240 seconds]
scox has joined #systemtap
Humble has quit [Ping timeout: 240 seconds]
mbenitez has joined #systemtap
<fche>
toothe, use .statement() rather than .function() probes to examine the internals of functions
wcohen has joined #systemtap
mbenitez has quit [Quit: Leaving]
mbenitez has joined #systemtap
mbenitez has joined #systemtap
mbenitez has quit [Changing host]
brolley has joined #systemtap
Humble has joined #systemtap
<toothe>
fche: that's interesting ,thanks!
<toothe>
also, why are there blacklisted functions? I don't fully understand that.
<fche>
hi toothe
<fche>
blacklisted functions (in kernel space) are there because the kernel cannot completely analyze itself well enough to put kprobes at all conceivable spots
<fche>
stap blacklists some functions for historical reasons - generally more conservative than the kernel, but for the same kinds of reasons
<toothe>
i see
<toothe>
can I disable the blacklist for a specific function?
<toothe>
so, I am doing a printf("%s\n", probefunc() );. I noticed that a function is called an unusual number of times within the kernel.
<toothe>
I initially thought for some reason the function is merely being called multiple times, but now I see that the parameters for the function differ.
<toothe>
Maybe I"m using the wrong code, but that strikes me as very odd.
<toothe>
am I making a mistake? Is there a reason a probe name is being repeated?
<fche>
the kernel blacklist is permanent. the systemtap blacklist can be suppressed with 'stap -g ...'
<fche>
re. unusual number of times ... that could be lots of things, like an inlined function
<fche>
depends on details
<toothe>
ahh...
<toothe>
yes, I do think that's being done.
<toothe>
I'm still learning the tool.
<toothe>
is there a way to suppress that and/or display the inline function names?
<fche>
and the tool gives you rather low level view into the system (and it's an imperfect view - we're also subject to the whims of the kernel & the compiler, and the occasonal stap bug)