This web mail archive is frozen.
This page is part of a frozen web archive of this mailing list.
You can still navigate around this archive, but know that no new mails
have been added to it since July of 2016.
Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.
I'm getting many "Source and destination overlap in memcpy" errors when
running my application on an odd number of procs.
I believe this is because the Allgather collective is using Bruck's
algorithm and doing a shift on the buffer as a finalisation step
tmprecv = (char*) rbuf;
tmpsend = (char*) rbuf + (size - rank) * rcount * rext;
err = ompi_ddt_copy_content_same_ddt(rdtype, rank * rcount,
Unfortunately ompi_ddt_copy_content_same_ddt does a memcpy, instead of
the memmove which is needed here. For this buffer-left-shift, any
forward-copying memcpy should actually be OK as it won't overwrite
itself during the copy, but this violates the precondition of memcpy and
may break for some implementations.
I think this issue was dismissed too lightly previously: