<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div text="#000000" bgcolor="#FFFFFF"><div class="moz-cite-prefix"><br></div><div class="moz-cite-prefix">Ciao Carlo,<br>
<br>
thanks for the hint. As far as I can see, the only point where
this kind of problem could arise is here<br>
<br>>>> grep -A6 __ELPA ./Modules/dspev_drv.f90</div><div class="moz-cite-prefix"><br>
--<br>
#ifdef __ELPA<br>
INTEGER :: nprow,npcol,my_prow, my_pcol,mpi_comm_rows,
mpi_comm_cols<br>
#endif <br>
<br>
IF( SIZE( s, 1 ) /= lds ) &<br>
CALL errore( ' pdsyevd_drv ', ' wrong matrix leading
dimension ', 1 )<br>
!<br>
--<br>
#ifdef __ELPA<br>
CALL BLACS_Gridinfo(ortho_cntx,nprow, npcol, my_prow,my_pcol)<br>
CALL GET_ELPA_ROW_COL_COMMS(ortho_comm, my_prow,
my_pcol,mpi_comm_rows, mpi_comm_cols)<br>
CALL SOLVE_EVP_REAL(n, n, s, lds, w, vv, lds ,nb
,mpi_comm_rows, mpi_comm_cols)<br>
IF( tv ) s = vv<br>
IF( ALLOCATED( vv ) ) DEALLOCATE( vv )<br>
#else<br>
--<br>
<br>
<br>
because the subroutine GET_ELPA_ROW_COL_COMMS internally calls
MPI_Comm_split, which seems to be the MPI subroutine which crashed
(according to the error message here below).<br>
Since the communicators mpi_comm_rows and mpi_comm_cols are just
used by ELPA in this subroutine, would it be safe to call<br>
MPI_Comm_free ( mpi_comm_rows, ierr )<br>
MPI_Comm_free ( mpi_comm_cols, ierr )<br>
just before #else ?<br>
<br>
If you don't see any potential problem, I would try this solution.<br>
<br>
<br>
Best,<br>
<br>
Gabriele<br>
<br>
<br>
<br>
On 10/23/2013 10:06 AM, Carlo Cavazzoni wrote:<br></div></div><blockquote type="cite"><div text="#000000" bgcolor="#FFFFFF"><div class="moz-cite-prefix">
</div>
<blockquote cite="mid:52678395.9020205@cineca.it" type="cite">
<div class="moz-cite-prefix">Ciao Gabriele,<br>
<br>
as far I understand with ELPA (which is build on a much deeper
communicator hierarchy wrt SCALAPACK)<br>
you hit a MPI environment limit (number of communicators).<br>
Even if the limit could be somehow increased, it sound like <br>
somewhere a communicator is created and not destroyed in the
relax work-flow.<br>
I guess it could be something related to temporary communicator
created to distribute atoms to processors.<br>
I don't remember exactly, but it can be checked easily searching
for communicator initialization calls<br>
<br>
carlo<br>
<br>
Il 22/10/2013 17:35, Gabriele Sclauzero ha scritto:<br>
</div>
<blockquote cite="mid:2B08A377-8F56-46FD-A57E-A1A526DF011B@epfl.ch" type="cite">
<pre wrap="">Dear all,
I've recently started using ELPA in place of Scalapack for large scale calculations and I indeed see a very good improvement of the performance.
Unfortunately, I've found a recurrent problem when running relax calculations (not due to the relaxation itself, though, I believe). The program crashes because of some MPI-related issues. The error message from the system looks as follows:
Abort(1) on node 1732 (rank 1732 in comm 1140850688): Fatal error in PMPI_Comm_split: Other MPI error, error stack:
PMPI_Comm_split(474).................: MPI_Comm_split(comm=0xc4000004, color=2, key=27, new_comm=0x1fffff7478) failed
PMPI_Comm_split(456).................:
MPIR_Comm_split_impl(228)............:
MPIR_Get_contextid_sparse_group(1071): Too many communicators
The crash happens during the Davidson diagonalization after a few ionic cycles of the relaxation (after roughly ~200 Davidson diagonalizations). It happens both with v.5.0.3 and with the latest SVN revision. If I compile with Scalapack in place of ELPA, both versions work fine (but are slower...).
Compilation details (see also attached make.sys):
BG/Q machine, XLF 14.1, XLC 12.1, ESSL 5.1, Scalapack 2.0.2
./configure --enable-openmp --with-elpa
The calculation was run on 256 nodes with the following command line:
runjob -n 2048 -p 8 --envs OMP_NUM_THREADS=4 --cwd [...] : /home/sclauzer/Codes/espresso/5.0.3_ELPA/bin/pw.x -nband 1 -npool 1 -ndiag 1024 -ntg 4 -in [...]
The system is quite large, a slab with ~1400 atoms and ~3000 bands. I don't know if the problem would show up for a smaller system or on fewer nodes, but I can try to provide a smaller example in order to investigate the problem more easily. Hopefully, this is something simple that the ELPA/Scalapack and BGQ experts among you can spot at a glance.
Best,
Gabriele
</pre>
</blockquote>
</blockquote>
<br>
</div>
</blockquote></div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-variant: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="font-family: Helvetica; font-size: medium; font-weight: normal; font-style: normal; "><span class="Apple-style-span" style="color: rgb(126, 126, 126); font-size: 16px; font-style: italic; "><br class="Apple-interchange-newline">§ Gabriele Sclauzero, EPFL SB ITP CSEA</span></div><div><font class="Apple-style-span" color="#7E7E7E"><i><span class="Apple-style-span" style="font-style: normal; "> PH H2 462,</span><span class="Apple-converted-space"> </span><span class="Apple-style-span" style="font-style: normal; ">Station 3, CH-1015 Lausanne</span></i></font></div></span></span>
</div>
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