Section: Software
PIOMan
Participants : Alexandre Denis, François Trahay.
PIOMan [46] is the event detector server used by the PM2 software suite. It aims at providing the other software components with a service that can guarantee a predefined level of “reactivity” to I/O events. It is typically used by NewMadeleine and PadicoTM to quickly react to network events, such as the arrival of a new packet.
PIOMan is able to isolate blocking system calls on dedicated threads so that the whole process is not suspended. It is actually a portable alternative to the Scheduler Activations model proposed by Anderson [48] and implemented in the LinuxActivations library [7] . PIOMan is also able to handle non-blocking detection methods. It thus choose the more suitable method to use depending on the processors' load and the communication library's preferences. This way, the application is reactive whatever the context is.
The level of reactivity provided by PIOMan allows NewMadeleine to make communications progress in the background (by making the rendezvous handshake progress for instance) and thus to fully overlap computation and communication [13] .
Thanks to a scalable task onloading mechanism, PIOMan is able to balance the processing of communication requests across the whole machine, message submission to the networks can be offloaded on idle core in order to overlap communication and computation even for eager message that require CPU-intensive memory copies [40] .
Madeleine , NewMadeleine and PadicoTM have been ported over PIOMan . Within our collaboration with the Argonne National Laboratory, MPICH2-Nemesis is being ported over PIOMan [36] . We also plan to use PIOMan in MPI implementations such as YAMPII (within the collaboration with the University of Tokyo).
This library, distributed as part of the PM2 software is developed and maintained by François Trahay . The software is freely available under the terms of the GNU General Public License version 2 at the following URL: http://runtime.bordeaux.inria.fr/pioman/ .
