Running rr from gud?

Running rr from gud?

[Skip Montanaro]

I recently encountered a reference to rr:

https://rr-project.org/

I saw nothing in the package list related to GUD support for rr. It
looks like it's basically gdb with some added special sauce, so adding
support shouldn't be terribly hard. I've never fiddled with gud
front-ends before and was hoping someone already had.

Off to read about gud customization...

Skip

Re: Running rr from gud?

[Joost Kremers]

On Sun, Oct 24 2021, Skip Montanaro wrote:
> I recently encountered a reference to rr:
>
> https://rr-project.org/
>
> I saw nothing in the package list related to GUD support for rr. It
> looks like it's basically gdb with some added special sauce, so adding
> support shouldn't be terribly hard. I've never fiddled with gud
> front-ends before and was hoping someone already had.

Under "rr features", there's a link "IDE integration" that takes you to this
page:

https://github.com/rr-debugger/rr/wiki/Using-rr-in-an-IDE

Emacs GUD/gdm-mi is mentioned under "known to work".

-- 
Joost Kremers
Life has its moments

Re: Running rr from gud?

[Skip Montanaro]

> Under "rr features", there's a link "IDE integration" that takes you to this
> page:
>
> https://github.com/rr-debugger/rr/wiki/Using-rr-in-an-IDE
>
> Emacs GUD/gdm-mi is mentioned under "known to work".

Thanks. Poked around for a couple minutes. Getting an error:

[FATAL /build/rr-S0CLEN/rr-5.3.0/src/PerfCounters.cc:310:start_counter()
errno: EACCES] Permission denied to use 'perf_event_open'; are perf
events enabled? Try 'perf record'.

which seems more Linux- than Emacs-related. I'll keep messing around.

Skip

Re: Running rr from gud?

[Emanuel Berg via Users list for the GNU Emacs text editor]

Skip Montanaro wrote:

>> Under "rr features", there's a link "IDE integration" that
>> takes you to this page:
>>
>> https://github.com/rr-debugger/rr/wiki/Using-rr-in-an-IDE
>>
>> Emacs GUD/gdm-mi is mentioned under "known to work".
>
> Thanks. Poked around for a couple minutes. Getting an error:
>
> [FATAL
> /build/rr-S0CLEN/rr-5.3.0/src/PerfCounters.cc:310:start_counter()
> errno: EACCES] Permission denied to use 'perf_event_open';
> are perf events enabled? Try 'perf record'.
>
> which seems more Linux- than Emacs-related. I'll keep
> messing around.

If you don't mind ... what is this thread about?

-- 
underground experts united
https://dataswamp.org/~incal

Re: Running rr from gud?

[Skip Montanaro]

>
> If you don't mind ... what is this thread about?
>

rr is a deterministic debugger. More details here:

https://rr-project.org/

I'm interested in it because there is a serious effort afoot to remove
Python's global interpreter lock (GIL). Its presence keeps more than one
Python-level from executing bytecode at the same time. The flip side is
that the GIL can hide mistakes related to concurrent data access. Once the
GIL is gone, some/many/most of those mistakes will be revealed. The
non-deterministic nature of multi-threaded execution makes it more
difficult to debug such code. rr looks like it might help, so I'm
considering it as a gdb adjunct/replacement, and since I debug C code in
Emacs I'd like to use rr in that environment.

Sorry for the long-winded explanation.

Skip

Re: Running rr from gud?

[tomas]

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On Sun, Oct 24, 2021 at 05:44:40PM -0500, Skip Montanaro wrote:
> > Under "rr features", there's a link "IDE integration" that takes you to this
> > page:
> >
> > https://github.com/rr-debugger/rr/wiki/Using-rr-in-an-IDE
> >
> > Emacs GUD/gdm-mi is mentioned under "known to work".
> 
> Thanks. Poked around for a couple minutes. Getting an error:
> 
> [FATAL /build/rr-S0CLEN/rr-5.3.0/src/PerfCounters.cc:310:start_counter()
> errno: EACCES] Permission denied to use 'perf_event_open'; are perf
> events enabled? Try 'perf record'.
> 
> which seems more Linux- than Emacs-related. I'll keep messing around.

What's the setting of your /proc/sys/kernel/perf_event_paranoid?

Perhaps lowering it a bit might give better results.

DISCLAIMER: I haven't much experience with that, much less an
idea what that might do to your box's security. The whole story
is somewhere here [1]. Don't do that on your Internet facing
server, less if it's running Apache. And so on ;-)

Cheers

[1] https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html#unprivileged-users

 - t

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Re: Running rr from gud?

[Skip Montanaro]

> What's the setting of your /proc/sys/kernel/perf_event_paranoid?
>
> Perhaps lowering it a bit might give better results.

Thanks for the pointer. It was set to 4. According to the man page
anything >= 2 is for user space tracing. I set it to 1 and that
particular issue went away.

Skip