RE: [PATCH v2] libgfortran: Replace mutex with rwlock

["Zhu, Lipeng" <lipeng.zhu@intel.com>]

> > Hi Lipeng,
> > 
> > > This patch try to introduce the rwlock and split the read/write to 
> > > unit_root tree and unit_cache with rwlock instead of the mutex to 
> > > increase CPU efficiency. In the get_gfc_unit function, the 
> > > percentage to step into the insert_unit function is around 30%, in 
> > > most instances, we can get the unit in the phase of reading the 
> > > unit_cache or unit_root tree. So split the read/write phase by 
> > > rwlock would be an approach to make it more parallel.
> >
> > No comment on the code itself, as yet... but I'd like to know how throroughly you tested it, using which tools, and on which programs.
> > Did you use valgrind --tool=helgrind or --tool=drd?  Since it is prone to race conditions, did you also test Fortran's asynchronous I/O?
> >
> > Best regards
> >
> >	Thomas
> 
> Hi Thomas,
> 
> I didn’t use valgrind and make check-fortran succeed in local. 
> And the tools/programs I used is pts/neatbench https://openbenchmarking.org/test/pts/neatbench
> 
> Best Regards,
> Lipeng Zhu

Hi Thomas,

Thanks for your comments, I just use valgrind --tool=helgrind or --tool=drd to test make check-fortran, no errors occurred.
==2609780== Helgrind, a thread error detector
==2609780== Copyright (C) 2007-2017, and GNU GPL'd, by OpenWorks LLP et al.
==2609780== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info
==2609780== Command: make check-fortran -j150
==2609780==
==2609780==
==2609780== Use --history-level=approx or =none to gain increased speed, at
==2609780== the cost of reduced accuracy of conflicting-access information
==2609780== For lists of detected and suppressed errors, rerun with: -s
==2609780== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

==2976599== drd, a thread error detector
==2976599== Copyright (C) 2006-2020, and GNU GPL'd, by Bart Van Assche.
==2976599== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info
==2976599== Command: make check-fortran -j150
==2976599==
==2976599==
==2976599== For lists of detected and suppressed errors, rerun with: -s
==2976599== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

BTW, can you give me some guidance of how to test Fortran's asynchronous I/O?

Best Regards,
Lipeng Zhu