Re: pthreads and UPC ....

From: Kathy Yelick (yelick_at_EECS_dot_Berkeley_dot_EDU)
Date: Sat Feb 14 2009 - 06:57:12 PST

  • Next message: Tahar Amari: "Re: pthreads and UPC ...."
    There are multiple UPC implementations, so it's often the case that  
    even if one does have a bug, another one will work.  Here's a list of  
    the compilers -- I hope someone will correct me if I've missed one:
    Berkeley UPC, bupc (
    Intrepid, gcc-upc (
    HP UPC (
    IBM UPC (
    Cray UPC (
    The first two are open source, so in principle the community at large  
    can also fix bugs in them.  Both also have active support teams and  
    there are regular (at least annual) releases of both.   The other  
    three are closed source commercial products and also have regular  
    releases and ongoing support.
    I think the quote you mentioned was only said once and later  
    retracted.  In particular, the Berkeley team does have people fixing  
    bugs,  so this kind of thing will be fixed, but as with most open  
    source projects, not necessarily within a few days.  This is true with  
    vanilla gcc today, so you should not feel less comfortable about  
    programming UPC than with C or C++.  In both cases you can buy  
    commercial compilers that come with higher level support guarantees or  
    use open source ones in which problems get fixed, but not necessarily  
    on a particular time scale.  The Berkeley and Intrepid compilers are  
    also highly portable and should run on any machine with shared memory  
    (pthreads, as you're discussing) or distributed memory (using GASNet).
    Katherine Yelick
    NERSC Division Director
    Lawrence Berkeley National Laboratory
    One Cyclotron Rd., MS 50B-4230
    Berkeley, CA  94720
    Email: kayelick_at_lbl_dot_gov
    Phone: 510-495-2431
    On Feb 14, 2009, at 4:58 AM, Tahar Amari wrote:
    > Hello Paul,
    > Many thanks for this detailed reply.
    > SInce I am  new with UPC, it is not a criticism at all but simply  
    > some thoughts before starting.
    > UPC seems certainlbut to be much easier to use than MPI.
    > I worry a little bit about bugs, and so how reliable it would be to  
    > put our projects to UPC.
    > I saw on the FAQs that there were some bugs and sometime some reply  
    > like " thanks for this bug
    > , we do not have anybody working on this right now , but will  
    > consider it the future".
    > Is is the same for all implementation, IBM, HP ?
    > Please understand again that I just want to enquire before making  
    > the "big jump" because
    > I feel very interested by UPC, but do not want to face compiler  
    > problems which I do not control,
    > when I hardly yet control the numerical or physical problems.
    > Thank you very much for your impression,
    > Tahar
    > URL :
    > Le 13 févr. 09 à 22:24, Paul H. Hargrove a écrit :
    >> Tahar,
    >> I regret that nobody appears to have replied to your questions yet  
    >> (or did not cc:ed the list if they did).
    >> The answer to your question is not a simple "Yes", but more a  
    >> "probably".
    >> Out runtime can optionally use pthreads internally for implementing  
    >> UPC threads within a single node, both with and without a network.   
    >> So, there is no fundamental problem with linking the pthreads  
    >> libraries.  Additionally, I am aware of at least on project that  
    >> uses pthreads in *addition* to UPC threads (as I suspect you are  
    >> asking).  In that case, each individual UPC thread retains its own  
    >> identity and can spawn pthreads to execute C (or C++ or FORTRAN, I  
    >> suppose) code, but the pthreads spawned by the user code cannot  
    >> execute UPC code because they do not correspond to any MYTHREAD  
    >> value.
    >> If you have more specific information about how you wish to mix  
    >> pthreads with UPC, let us know and we might be able to clarify  
    >> further.
    >> -Paul
    >> Tahar Amari wrote:
    >>> Hello,
    >>> One of my code use Pthreads.
    >>> Is it possible to still use this piece of code with UPC ?
    >>> Many thanks
    >>> Tahar
    >> -- 
    >> Paul H. Hargrove                          PHHargrove_at_lbl_dot_gov
    >> Future Technologies Group                 Tel: +1-510-495-2352
    >> HPC Research Department                   Fax: +1-510-486-6900
    >> Lawrence Berkeley National Laboratory

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