My point was just that we support the current implementation of pthreads - not any old one.
Also, to clarify: Jeff actually tests to see what the thread library does. We only use the Linux kernel version when cross-compiling since we cannot, in that case, actually test the support. We know that old Linux kernels have the old implementation, so we exclude them. Anything else is hit-miss when cross-compiling. On Mar 15, 2011, at 4:46 PM, Paul H. Hargrove wrote: > Sorry, I stated my facts backwards. > CORRECTED facts: > > +The old "LinuxThreads" implementation is the one that gave DIFFERENT pids to > each pthread. > + "NPTL" is the current implementation of Pthreads for Linux, and the one > giving a single pid shared by all pthreads. > > So, I hope Ralph's statement is similarly reversed, because "LinuxThreads" as > not been maintained in years. > > -Paul > > On 3/15/2011 3:40 PM, Ralph Castain wrote: >> I believe the test is intended strictly for Linux threads. I don't believe >> we have ever (intentionally) supported any other thread library in such >> environments. >> >> I'll leave it to Jeff to decide if he feels this is an issue. >> >> >> On Mar 15, 2011, at 4:27 PM, Paul H. Hargrove wrote: >> >>> I'd like to point out that it is libpthread and the arguments it passes to >>> clone(), NOT the Linux kernel version, that is the determining factor (at >>> least if you have a 2.6.x kernel). The "LinuxThreads" implementation of >>> Pthreads will give the one-pid-to-rule-them all behavior, while the NPTL >>> implementation gives unquie pids under any 2.6.x kernel and even w/ some >>> 2.4.x kernels from Red Hat. >>> >>> I have encountered systems on which dynamic linking gave NPTL and static >>> linking gave LinuxThreads. That is a "gottcha" that I am not certain Jeff >>> and Ralph have taken into account. >>> >>> Note that I have no objection to "we don't support this", but fear that >>> detection of that situation may be flawed. >>> >>> -Paul >>> >>> On 3/15/2011 2:14 PM, Ralph Castain wrote: >>>> Hi folks >>>> >>>> Jeff and I encountered a problem when cross-compiling OMPI for Linux. >>>> Turned out that we had an old test in the code that looked for threads to >>>> have different pids. Since it couldn't be tested when cross-compiling, the >>>> test simply assumed this was the case for Linux under those conditions - >>>> which broke the build for current Linux kernels. >>>> >>>> Different pids for threads was last seen in the old RH 4 series (kernel >>>> 2.6.9 or so). Some code (e.g., waitpid) was also provided to support this >>>> unusual situation - this code was in fact broken when we updated the event >>>> library. So even if we were in an old kernel, the code base would neither >>>> compile nor run. >>>> >>>> Rather than trying to continue to support these old kernels, we have >>>> removed all the stale code that was covered by >>>> OPAL_THREADS_HAVE_DIFFERENT_PIDS. This removed some complexity from a few >>>> PLM modules and removed the broken code. >>>> >>>> Jeff modified the corresponding .m4 test so we now detect an older kernel, >>>> print out a nice "we don't support this" message (along with noting that >>>> earlier versions of OMPI do), and then abort the build. >>>> >>>> If you know of some reason to restore support for old Linux kernels, and >>>> someone willing to do the work to "refresh" that support, please let us >>>> know. >>>> >>>> Ralph& Jeff >>>> >>>> >>>> _______________________________________________ >>>> devel mailing list >>>> de...@open-mpi.org >>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel >>> -- >>> Paul H. Hargrove phhargr...@lbl.gov >>> Future Technologies Group >>> HPC Research Department Tel: +1-510-495-2352 >>> Lawrence Berkeley National Laboratory Fax: +1-510-486-6900 >>> >>> _______________________________________________ >>> devel mailing list >>> de...@open-mpi.org >>> http://www.open-mpi.org/mailman/listinfo.cgi/devel >> >> _______________________________________________ >> devel mailing list >> de...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/devel > > -- > Paul H. Hargrove phhargr...@lbl.gov > Future Technologies Group > HPC Research Department Tel: +1-510-495-2352 > Lawrence Berkeley National Laboratory Fax: +1-510-486-6900 > > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel
