Re: PLEASE HELP regarding System Tap

[fche at redhat dot com (Frank Ch. Eigler)]

"Khushboo Goel" <kgoel@usc.edu> writes:

> [...]
>>> i am using an aggregate variable to store all information, but i
>>> have huge data around 50K packets in one run ,which gives me
>>> overflow buffer[...]
>>
>> You may need to use a larger MAXMAPENTRIES (see the stap(1) man page),
>> or explicitly size the buffering aggregate global
>>
>>   global buffer[50000]
>
> I don't want to use variable like this as, it doesn't solve my problem.

Could you explain why you think so?  You haven't transcribed your
error message(s) yet, so we are still only guessing.


> Yea i am posting my full script for now, its under work....  I have
> commented most of thing.

Thanks.

> Is it possible in System Tap that i can find address of the location
> in the memory which is assign to the buffer?? So that i can write
> directly to the location.

I'm sorry, I don't understand.  You should not have to use any unusual
measures just to produce tracing output.


Looking at your script, you are doing one space-hungry and one
time-hungry thing that may each need change.  Your npr_pktsize[] array
will be both tall and wide -- potentially many elements, each a wide
histogram.  That will consume lots of memory to store.  The whole
array will also take lots of time (statements) and (buffer) space to
print out with that unlimited foreach().  Depending on which resource
systemtap detects as exhausted, you may get different error messages.
For each of them, there is some sort of countermeasure.

I'll write up a wiki page with tips about the various alternatives,
but you could in the mean time share your errors so we can point you
to the specific one you're hitting.

- FChE