There are two potential places you could use: * the vpid itself is 32-bits in size - we are quite some years away from needing all of them, so taking the upper-most bit for this purpose should be okay
* the lower 16-bits of the jobid is the local jobid - i.e., the number of times someone called “comm_spawn”. The code for recycling those has gone a tad stale, but it wouldn’t be hard to recover it. I doubt someone will call comm_spawn more than 2^15 times without at least one of those completing so we can reuse the jobid, and so it should be safe to take the upper bit of that field. Frankly, I thought the second option was what Nathan had intended, so I’m surprised to see us masking at the 64-bit level. This touches the mpirun part of the jobid (the upper 16-bits), which is a hash based on the hostname and OS pid. Stripping a bit from that is risky and I definitely wouldn’t advise it. > On Feb 5, 2016, at 7:48 PM, Gilles Gouaillardet > <gilles.gouaillar...@gmail.com> wrote: > > Thanks George, > > I will definitely try that ! > > back to the initial question, has someone any thoughts on which bit(s) we can > lose when using cutoff ? > > Cheers, > > Gilles > > On Saturday, February 6, 2016, George Bosilca <bosi...@icl.utk.edu > <mailto:bosi...@icl.utk.edu>> wrote: > In addition shouldn't we use uintptr_t instead of the intptr_t to cope with > the MSB during the shifting operations? > > George > > On Feb 5, 2016 10:08 AM, "Jeff Squyres (jsquyres)" <jsquy...@cisco.com <>> > wrote: > On Feb 5, 2016, at 9:26 AM, Gilles Gouaillardet > <gilles.gouaillar...@gmail.com <>> wrote: > > > > static inline opal_process_name_t ompi_proc_sentinel_to_name (intptr_t > > sentinel) > > { > > sentinel >>= 1; > > sentinel &= 0x7FFFFFFFFFFFFFFF; > > return *((opal_process_name_t *) &sentinel); > > } > > I don't have much of an opinion on any of the other stuff here, but I note > that this is unsafe. I know we don't really care about non-64 bit these > days, but we shouldn't be knowingly breaking it. Instead of ANDing with a > fixed constant, shouldn't it be something like: > > intptr_t mask = ~1 >> 1; > sentinel &= mask; > > -- > Jeff Squyres > jsquy...@cisco.com <> > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > <http://www.cisco.com/web/about/doing_business/legal/cri/> > > _______________________________________________ > devel mailing list > de...@open-mpi.org <> > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > <http://www.open-mpi.org/mailman/listinfo.cgi/devel> > Link to this post: > http://www.open-mpi.org/community/lists/devel/2016/02/18557.php > <http://www.open-mpi.org/community/lists/devel/2016/02/18557.php> > _______________________________________________ > devel mailing list > de...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > Link to this post: > http://www.open-mpi.org/community/lists/devel/2016/02/18563.php > <http://www.open-mpi.org/community/lists/devel/2016/02/18563.php>
