GCC: OpenMP posix pthread

GCC: OpenMP posix pthread

[Erotavlas_turbo]

Hi,

I'm starting to use Helgrind a tool of Valgrind. I read on the manual the following statement:
Runtime support library for GNU OpenMP (part of GCC), at least for GCC versions 4.2 and 4.3. The GNU OpenMP runtime library (libgomp.so) constructs its own synchronisation primitives using combinations of atomic memory instructions and the futex syscall, which causes total chaos since in Helgrind since it cannot "see" those.

In the latest version of GCC, is this still true or now the OpenMP uses the standard POSIX pthread?

Thank you

Re: GCC: OpenMP posix pthread

[Tim Prince]

On 2/19/2012 9:42 AM, Erotavlas_turbo@libero.it wrote:

> I'm starting to use Helgrind a tool of Valgrind. I read on the manual the following statement:
> Runtime support library for GNU OpenMP (part of GCC), at least for GCC versions 4.2 and 4.3. The GNU OpenMP runtime library (libgomp.so) constructs its own synchronisation primitives using combinations of atomic memory instructions and the futex syscall, which causes total chaos since in Helgrind since it cannot "see" those.
>
> In the latest version of GCC, is this still true or now the OpenMP uses the standard POSIX pthread?
>

Do you have a specific OS family in mind?


-- 
Tim Prince

Re: GCC: OpenMP posix pthread

[Erotavlas_turbo]

Hi,

I have found the solution i.e. the developers of GCC have found it. The latest version of GCC 4.6.3 can be used with Helgrind. See here for more detail http://gcc.gnu.org/onlinedocs/libstdc++/manual/debug.html#debug.races


Best Regards

Salvatore

Re: GCC: OpenMP posix pthread

[Erotavlas_turbo]

Hi,

thank you for your reply. So I cannot use the Helgrind tool without disabling the futexes. Do you know if exist a open source thread analyzer?

Thank you

Re: GCC: OpenMP posix pthread

[Jakub Jelinek]

On Tue, Feb 21, 2012 at 04:50:58PM +0100, Erotavlas_turbo@libero.it wrote:
> Nobody can answer to my question?

You can configure gcc not to use futexes in libgomp (--disable-linux-futex),
but the default is to use them for performance reasons.

	Jakub

Re: GCC: OpenMP posix pthread

[Erotavlas_turbo]

Nobody can answer to my question?

Thank you

Salvatore Frandina

Re: GCC: OpenMP posix pthread

[Erotavlas_turbo]

> On 2/19/2012 9:42 AM, Erotavlas_turbo@libero.it wrote:
>
> > I'm starting to use Helgrind a tool of Valgrind. I read on the manual the following statement:
> > Runtime support library for GNU OpenMP (part of GCC), at least for GCC versions 4.2 and 4.3. The GNU OpenMP runtime library (libgomp.so) constructs its own synchronisation primitives using combinations of atomic memory instructions and the futex syscall, which causes total chaos since in Helgrind since it cannot "see" those.
> >
> > In the latest version of GCC, is this still true or now the OpenMP uses the standard POSIX pthread?
> >
>
> Do you have a specific OS family in mind?
>
>
> --
> Tim Prince
>

Yes, I'm talking about the UNIX OS (Linux, MacOSx). The tool valgrind is only available for these systems.


Salvatore Frandina