Thanking you all very much for the reply.
I would request to have some reference about what Tim Prince & Andreas has
said.
Tim said that OpenMPI has had effective shared memory message passing. Is
that anything to do with --enable-MPI-threads switch while installing
OpeMPI?
regards,
AA
justifying this and comment/modify above two
justifications. Better if I you can suggent me to quote some reference of
any suitable publication in this regard.
best regards,
Amjad Ali
which one to use MTL or
BTL?
Thank you.
Regards,
Amjad Ali
Perhaps often it is more useful to use MPI_WAIT rather than MPI_TEST type
fucntions, because at MPI_WAIT point it will be taken care of communication
completion, automatically, which may be necessary before going ahead. with
MPI_TEST it would become the responsibility of the programmer to handle th
y model locally at each node, evading unnecesary I/O through the
> nwetwork, what do you think?
>
>
>
> On Thu, Jul 22, 2010 at 5:27 PM, amjad ali wrote:
> > Hi Cristobal,
> >
> > Note that the pic in http://dl.dropbox.com/u/6380744/clusterLibs.png
> > shows t
Hi Cristobal,
Note that the pic in http://dl.dropbox.com/u/6380744/clusterLibs.png
shows that Scalapack is based on what; it only shows which packages
Scalapack uses; hence no OpenMP is there.
Also be clear about the difference:
"OpenMP" is for shared memory parallel programming, while
"OpenMPI"
from the start of your program, after a certain activitiy, say after 10
lines use print statement with STOP/EXIT , also printing processor rank.
If u get all the processors than its fine. Move this printing little ahead
and get printing again. Repeat this process until u reach the place of
fault.
Based on my experiences, I would FULLY endorse (100% agree with) David
Zhang.
It is usually a coding or typo mistake.
At first, Ensure that array sizes and dimension are correct.
I experience that if openmpi is compiled with gnu compilers (not with Intel)
then it also point outs the subroutine ex
Dear E. loh,
Thank u very much for your help.
Actually i was doing the same according to your earlier suggestions
---and now in the program; but error was there.
At last i found the blunder made by myself.
It was a typo mistake infact of a variable name.
i will let u know about the performan
and it's conceivable that you might have better performance with
>
> CALL MPI_ISEND()
> DO I = 1, N
> call do_a_little_of_my_work() ! no MPI progress is being made here
> CALL MPI_TEST()! enough MPI progress is being made here
> that the receiver has something t
I guess that if the receiver want to ensure that the sender should send data
only when the receiver will be able/free to receive data,
then use MPI-Barriers.
On Mon, Jun 28, 2010 at 12:53 PM, David Zhang wrote:
> Use MPI_Iprobe. It's a nonblocking probe that allow you to see if a
> message i
Dear E. Loh.
**
>
>
> Another is whether you can overlap communications and computation. This
> does not require persistent channels, but only nonblocking communications
> (MPI_Isend/MPI_Irecv). Again, there are no MPI guarantees here, so you may
> have to break your computation up and insert MP
>
> You would break the MPI_Irecv and MPI_Isend calls up into two parts:
> MPI_Send_init and MPI_Recv_init in the first part and MPI_Start[all] in the
> second part. The first part needs to be moved out of the subroutine... at
> least outside of the loop in sub1() and maybe even outside the
> 1000
Hi Jeff S.
Thank you very much for your reply.
I am still feeling some confusion. Please guide.
The idea is to do this:
>
>MPI_Recv_init()
>MPI_Send_init()
>for (i = 0; i < 1000; ++i) {
>MPI_Startall()
>/* do whatever */
>MPI_Waitall()
>}
>for (i = 0;
Hi all,
I observed MPI_ISEND & IRECV performing little better than persistenent
communication; although I was hoping/desiring the opposite case??
What is the be the best way of using MPI persistent communication in an
iterative/repetative kind of code about calling MPI_Free(); Should we call
MPI
Dear Hammad,
Can you please have a RUN with "sufficiently Larger Problem Instance"? Then
see what happens!!
Sufficientmay be 10 times greater than that you used.
best regards,
Amjad Ali.
On Fri, Mar 12, 2010 at 3:10 AM, Hammad Siddiqi wrote:
> Dear All,
> Is this the c
Hi,
thanks T.Prince,
Your saying:
"I'll just mention that we are well into the era of 3 levels of programming
parallelization: vectorization, threaded parallel (e.g. OpenMP), and
process parallel (e.g. MPI)." is a really great new learning for me. Now I
can perceive better.
Can you please expl
Hi,
Suppose we run a parallel MPI code with 64 processes on a cluster, say of 16
nodes. The cluster nodes has multicore CPU say 4 cores on each node.
Now all the 64 cores on the cluster running a process. Program is SPMD,
means all processes has the same workload.
Now if we had done auto-vectoriz
s (10, 20 or 30 may be) in the header
while making call to a subroutine.
Which way is quite fast and efficient over the other?
Thank You for your kind attention.
with best regards,
Amjad Ali.
benefit/efficiency?
Better if any body can refer to some tutorial/example-code on this.
Thank you for you attention.
With best regards,
Amjad Ali.
/portion in the recv_array.
Is this scheme is quite fine and correct.
I am in search of efficient one.
Request for help.
With best regards,
Amjad Ali.
; T. Rosmond
>
>
>
> On Fri, 2009-11-06 at 17:44 -0500, amjad ali wrote:
> > Hi all,
> >
> > I need/request some help from those who have some experience in
> > debugging/profiling/tuning parallel scientific codes, specially for
> > PDEs/CFD.
> >
>
Hi all,
I need/request some help from those who have some experience in
debugging/profiling/tuning parallel scientific codes, specially for
PDEs/CFD.
I have parallelized a Fortran CFD code to run on
Ethernet-based-Linux-Cluster. Regarding MPI communication what I do is that:
Suppose that the gri
Hi all,
I want to get the elapsed time from start to end of my parallel program
(OPENMPI based). It should give same time for the same problem always;
irrespective of whether the nodes are running some or programs or they are
running only that program. How to do this?
Regards.
ils on your
> installation, your system and your shell.
>
> Greetings, Jakob
>
My installation is ROCKS-5 (64 bit), 4-nodes with Xeon3085, bash shell.
Compilers are GNU 64-bit.
Next??
>
> amjad ali wrote:
> > Hi all,
> > A simple program at my 4-node ROCKS cluster
different location than
the ./sphere.
Openmpi is installed with GNU compilers.
Best Regards,
Amjad Ali
Hello Mr. Eugene Loh,
THANK YOU VERY MUCH, IT WORKED. I used both ISEND and IRECV and then a
combined call to WAITALL with MPI_STATUSES_IGNORE.
with best regards,
Amjad Ali.
On Fri, Aug 14, 2009 at 6:42 AM, Eugene Loh wrote:
> amjad ali wrote:
>
> Please tell me that if have mult
On Fri, Aug 14, 2009 at 1:32 AM, Eugene Loh wrote:
> amjad ali wrote:
>
> I am parallelizing a CFD 2D code in FORTRAN+OPENMPI. Suppose that the grid
> (all triangles) is partitioned among 8 processes using METIS. Each process
> has different number of neighboring processes. Suppo
KIND ATTENTION.
With best regards,
Amjad Ali.
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