notes ui call 20070214

notes ui call 20070214

[Elena Zannoni]

In case these are helpful, here are my notes for today's call.

Attendees:
RH: Andrew, Phil, Rich, Chris, Sami, Nurdin, Mike, Tim, Mark, Jonathan
Oracle: Kris, Elena


HPDF interface, with fhpd. -- Tim and Stan

Demonstrated command set with attach, go, halt, where, help, list

Tim: stop the world or stop individual threads? Right now it's stop the 
world.
But underlying mechanism to do stop each thread is there.

Tab completion: demoed

go is different from continue in hpdf. continue is blocking the hpd
interface, go doesn't. I.e. go is async, continue is sync.

breakpoints: can set breakpoints, and run (there is a bug, though that
Tim has a fix for, not checked in yet). Break syntax right now is
break <filename> <linenumber> needs refining.

print command can display arrays, array elements and classes

Can also print in different formats. print <var> -format [x|o]

Help <command> is totally broken


Can do "what <var name>" displays the type of the variable or function

disassembler: not hooked up to the hpd yet. Works in the source
window. Not demoed.

display of registers: there needs to be a refactoring. Not demoed.

volatile attribute can make a variable stick around even with optimization.

how about logging, should that be an option on start up of fhpd.

compatibility with gdb command set. it's needed, maybe a set of aliases.



Custom observers -- Sami

cagney: use "catch" instead of "Print" in the actions. To avoid
printing the whole backtrace for instance, since it can be too
long. Just show that the event has happened and stop there.

Fork observer has 2 callback functions: in one the parent is paused,
in the other the child is paused.  Picking an action on either thread,
the thread will be invoking the proper callback.

Some actions take arguments, like "add observer". Enter args in the
box to the right of the action selection box. There is an
autocompletion feature that is now broken, on the args.

no way to tell if all filters are valid or not for a given action if
filters and actions have been applied.

plus/minus buttons are confusing. Minus on the first one: what does it
do? unclear.

Is order of actions important?

How common is it to create custom observers? Frysk developers use them.

Custom written events are needed. Written using code.

Filters should be a short list

Interactions between actions and the radio buttons at the
bottom. Users could construct contradictory events/actions.

Open issue: How to best bind events to threads. One event can apply to
many threads


Conference call issues:

1. Wednesday 9:30AM seems to be better than Thursday 9:30AM. All agree
   to move call to Wed.

2. Request to open up the RH only conf call to all. For general status
   of the project, who works on what, progress reports, and
   dependencies/issue with other components (kernel, gcc, libunwind,
   etc) RH has things that cannot be discussed openly, will need to
   figure out how to avoid having 3 meetings. Elena's suggestion is to
   use the Wed call, and shorten the GUI part.

Re: notes ui call 20070214

[Mark Wielaard]

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Hi Elena,

Thanks for taking notes!

On Wed, 2007-02-14 at 11:26 -0500, Elena Zannoni wrote:
> Tim: stop the world or stop individual threads? Right now it's stop the 
> world.
> But underlying mechanism to do stop each thread is there.

What you can do at all times is add an Instruction TaskObserver.

     * Interface used to notify that a Task has executed a single
     * instruction. <code>updateExecuted</code> is called as soon as
     * the Instruction observer is added to the Task. And whenever the
     * Task starts running again (isn't blocked or suspended) it will
     * be called on each instruction being executed.
     * <p>
     * This TaskObserver can also be used for executing code that
     * needs the Task to be (temporarily) blocked or suspended as soon
     * as possible. <code>updateExecuted()</code> will be called as
     * soon as this observer has been properly added, and at that time
     * the Task is suspended to make it possible to inspect the Task
     * state. If no other action is request, the method can then just
     * delete the observer from the Task again.

> volatile attribute can make a variable stick around even with optimization.

And I only added volatile to make sure they wouldn't get optimized away.
Filed bug report #4048 for this. (Does the fhpd have a tracker bug?)

> Help <command> is totally broken

New bug #4050 This would be really useful!

> compatibility with gdb command set. it's needed, maybe a set of aliases.

New bug #4049

> 2. Request to open up the RH only conf call to all. For general status
>    of the project, who works on what, progress reports, and
>    dependencies/issue with other components (kernel, gcc, libunwind,
>    etc) RH has things that cannot be discussed openly, will need to
>    figure out how to avoid having 3 meetings.

Note that "cannot be discussed openly" is more "not very frysk related".
I would vote for less phone talk and more discussion on list by email.
Unless there are very good minutes made and posted (you make great
minutes btw!) there is big chance of things falling through the cracks.

If we discuss some things more on the list (just simple things like
'heay, has anybody recently tried a 2.6.20 kernel? Does it pass our
frysk-import tests?') that would be really good to have an automatic
record for everybody, even if you cannot make a call.

Cheers,

Mark

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