systemtap GUI Requirements

[Vara Prasad]

Ryan Morse wrote:

> Hi-
>
> We have finished writing the systemtap GUI requirements document.  If 
> interested, please look over the pdf I attached.
>
> -Ryan

Sorry for the delay in my review. This is a good start for the 
requirements, i think these requirements are a good basic building block.
I have divided my comments into two sections general and specific 
comments to the doc.

General:
We need a section that specifies the h/w and s/w environment that is 
needed to install the GUI, for example this section lists if one needs 
to download Eclipse or not etc.

I think we need to add a section called intended audience or customers, 
that should cover who all e.g. kernel developers, sysadmins etc. could 
use this and how would they benefit from the GUI vs the existing command 
line.

If you look at what is the purpose of SystemTAP, it is a tool to do 
functional and performance analysis in a production environment in real 
time (realtime i meant here is almost instant to the happening of an 
event). The customer base for SystemTAP includes all the way from 
sysadmins to kernel developers. When i read through the document i got a 
feeling that the proposed requirements are to develop an IDE for people 
to develop systemtap scripts. This to me is useful but not really giving 
me a GUI interface for functional and performance analysis (which is the 
goal of systemtap).  In my view GUI should present a dash board of 
various resources in the system like memory, cpu, I/O, n/w, locks etc. 
Once i have that i should be able to kind of watch how resources are 
being used and should be able to freely drill down on any resource.  A 
similar view can be done for applications using the application specific 
tapsets behind the screens.

For example if i have a high level question "my system is running low on 
memory", the GUI should let me drill down on which process is hogging 
the memory, once i figure out the process i should know be able to get 
the details of from what are all the different memory pools this process 
is allocating memory. Another related question i may have (which many 
times Linux customers run into on x86) is i am running out of lowmem, 
GUI should be able to let me find out who are all the top 10 consumers 
of lowmem. Similarly for locking i should be able to see who is holding 
what locks, what is the queue statistics (min, max, avg etc.) on various 
locks.

GUI should use behind the screens systemtap and predefined scripts and 
tapsets to gather the data. GUI should generate various probe modules as 
needed to help user explore various system properties.  Unless a user 
explicitly would like to develop their own probe scripts the probe IDE 
interface should be mostly in the background. Hope this gives an idea of 
what my view of SystemTAP GUI for the wide customer base we are trying 
to serve.

Specific:
Following are the specific comments on the submitted document.

Pg 4: It says no easy way to view predefined functions, what function 
means here?
section 2.2: It says it should allow addition existing functions. It is 
not clear what do you mean by existing functions.
2.3: In situations .. sentence can be made better. A suggested re write 
is "In situations where long response times are unavoidable as an 
example running systemtap with a large module, a visual cue will be 
displayed it inform the user of the activity."
3.1.1: It says embedded will be checked for unsafe dereference of 
pointers. Exactly what we are planning to do here and how are we 
checking these?
3.1.3: What exactly you mean by periodically running the translator? 
Will it be done in the background or foreground? How do you decide when 
to run the translator? Can i make changes while the translator is 
running? This part needs to be explained better to answer some of these 
questions.
3.2: It says counting line no. is error prone, what is the relevance of 
counting line no. here?
3.3: What exactly you mean be in addition all items in the current file 
will be added to the tree?
3.3.1: Function browser: I am guessing your covering here built in 
functions like log(), trace() etc. I look at these as library functions 
for the systemtap language, similar to libc functions for "C" language. 
When you take an "C" IDE, these library functions are not shown in the 
source development but they are available under help, i think we should 
follow that model? We shouldn't worry about showing file where these 
functions are implemented. We should look at these more as builtin 
functions of the language.
3.3.2: The tapset browser also shouldn't organize based on the 
Folder->file->alias method, instead it should be arranged based on the 
functional area of the kernel and applications.
3.4: Conditional filter selector: This section is not clear, are you 
referring to conditional blocks like if, while etc. or some thing else. 
An example would help understand this better. If you are referring to 
if, while etc. i am not sure why you want to have a filter selector for 
that as they are part of the language. In other words you are not 
planning to provide GUI element to every basic block of the language 
then why these conditional statements.
3.5: Traces: This section is not at all clear. After discussing with 
Hien i understand the intention but document doesn't communicate that 
intention. I would suggest adding some examples would help make this 
section clear.
4.1: The only difference is .. sentence has two instead words.
4.2: The second paragraph says a new tapset will be developed that 
specifies the functions that will format the data for GUI to plot. This 
sentence is bit vague, what exactly you mean by the functions, don't we 
already have builtin functions to format the data, adding some examples 
would help.
4.4:  What is an event for the purpose of this discussion? Can you give 
some examples.
5.1: This section states the user needs to have a basic understanding of 
SystemTAP and Kprobes, why and what exactly the kind of knowledge about 
these underlying technologies.
6.2:  Is there a product called Rationale for testing? I think there is 
a product from ex-Rationale now IBM company for testing but i doubt its 
name is Rationale.
7.1 The last sentence of  the first paragraph says " or the amount 
certain things are accessed" , this is not very clear, suggest a rewrite 
to make it clear.
The second paragraph says it is not built into SystemTAP GUI, why not 
make it as a panel in the GUI.

bye,
Vara Prasad