i must apoligize first cuz my english sux yeah i know... and maybe
thats why i cant seen to make you guys understand...
ill paste the source code here... but this is only my test program...
what im really trying to do is to check if theres any message sent to
a node (in the test case, the node 1), and if there is, process that
message...if not, try again...
now heres the small test program:
#include <stdio.h>
#include <mpi.h>
#include <unistd.h>
#define TAG 1001
int main(int argc, char* argv[]) {
MPI_Request req;
MPI_Status status;
int size, rank;
int num, flag;
int i, errCode;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
printf ("starting waiting....\n");
if (rank == 1) {
flag = 0;
while (!flag){
sleep(1);
errCode = MPI_Iprobe (MPI_ANY_SOURCE, MPI_ANY_TAG,
MPI_COMM_WORLD, &num,&status) ;
if (errCode != MPI_SUCCESS) {
switch (errCode) {
case MPI_ERR_COMM:
printf ("comm error\n");
break;
case MPI_ERR_TAG:
printf ("TAG ERR\n");
break;
case MPI_ERR_RANK:
printf ("rank \n");
break;
}
}
}
printf ("New message! receiving....\n");
errCode = MPI_Recv (&num, 1, MPI_INT, MPI_ANY_SOURCE,
MPI_ANY_TAG, MPI_COMM_WORLD, &status);
if (errCode != MPI_SUCCESS) {
switch (errCode) {
case MPI_ERR_COMM:
printf ("comm error\n");
break;
case MPI_ERR_TAG:
printf ("TAG ERR\n");
break;
case MPI_ERR_RANK:
printf ("rank \n");
break;
}
}
printf ("Received: %d\n", num);
}
else if (rank == 0) {
num= 123;
scanf ("%d", &num);
errCode = MPI_Send (&num, 1, MPI_INT, 1,TAG, MPI_COMM_WORLD);
if (errCode != MPI_SUCCESS) {
switch (errCode) {
case MPI_ERR_COMM:
printf ("comm error\n");
break;
case MPI_ERR_TAG:
printf ("TAG ERR\n");
break;
case MPI_ERR_RANK:
printf ("rank \n");
break;
}
}
printf ("Sent! \n");
}
printf ("%d is saying bye...\n", rank);
MPI_Finalize();
return 0;
}
its now using the iprobe to check for messages... i also tried the
irecv but the result is the same: it never receives a msg... is there
anything wrong with my code? am i using probe correctly? is there any
other way to do the same (wich is to preemptively receive a msg)?
i hope i could make myself clear now.. im not good with words guys and
for that i apologize...
ty in advance...
On 7/5/05, Jeff Squyres <jsquyres_at_[hidden]> wrote:
> No, I think David perfectly understood your problem (I assume you meant
> "Iprobe" or "Irecv" -- there is no MPI function call named "Ipost").
>
> If the value of TAG does not match on the sender and the receiver, you
> will see "lock up" behavior because the receive (or probe or whatever
> you are using) will not match, and therefore it will not complete.
> Note, however, that you only showed code for the Irecv case (BTW, when
> you immediately follow Irecv with Wait, it's pretty much exactly like
> calling Recv -- you're not gaining any of the benefits of non-blocking
> communication). You mentioned that you changed your code to poll over
> (assumedly) Iprobe. Make sure that you're not calling Irecv in this
> loop -- that you're only looping on the flag value from Iprobe (and
> ensuring that the tag is the same between the sender and receiver).
>
> You might want to take a quick MPI tutorial to get more familiar with
> these kinds of issues. There's a good one at
> http://webct.ncsa.uiuc.edu:8900/public/MPI/, for example. I also wrote
> a magazine column about MPI for a while; back-issues, with lots of
> background information on MPI (including one issue where I give my
> opinion about why the probe functions are evil), can be found at
> http://cw.squyres.com/.
>
>
> On Jul 4, 2005, at 5:15 PM, Marcelo Fukushima wrote:
>
> > i think your not getting my problem.. ill try to explain myself better:
> > the MPI_Ipost is not working the way its suppose to... for instance,
> > in my example, i send n1 a msg from n0 (input by stdin)... while n1
> > keep pooling the msg buffer (by probing it, nonblocking) until it says
> > n1 got a message to receive... them, he receives, print it and
> > exits....
> > what is happening right now is the probe never returns TRUE (i mean
> > its flag, not the return itself wich is always MPI_SUCCESS), even
> > tough i use the blocking send on the n0 (and this blocking send goes
> > normally as well)... so, the real question comes now: am i using probe
> > correctly? i also tried pooling with the unsync receive, but the
> > result is the same...
> >
> > ty in advance...
> >
> > On 7/4/05, David Cronk <cronk_at_[hidden]> wrote:
> >> This really doesn't seem like a LAM specific situation, so I am
> >> reluctant to
> >> continue in this forum. The usenet group comp.parallel.mpi is a good
> >> source
> >> for general MPI questions.
> >>
> >> The only other thing I see right now is I don't see where TAG is
> >> defined.
> >> Make sure TAG has the same value for both sender and receiver.
> >>
> >> Dave.
> >>
> >>
> >> Marcelo Fukushima wrote:
> >> ok ty didnt realise that... but it aint working still...
> > On 7/4/05, David
> >> Cronk <cronk_at_[hidden]> wrote:
> >
> >> You are sending from rank 0 to rank 0. You need to send to rank
> >> 1.
> >
> > Dave.
> >
> > Marcelo Fukushima wrote:
> >
> >
> >> hello guys!!! another noobish question...
> >
> > im trying the simplest of all
> >> non-blocking routine and it simply locks up...
> >
> > int main(int argc, char*
> >> argv[]) {
> > MPI_Request req;
> > MPI_Status status;
> > int size, rank;
> > int num,
> >> flag;
> > int i;
> > MPI_Init(&argc, &argv);
> > MPI_Comm_rank(MPI_COMM_WORLD,
> >> &rank);
> > MPI_Comm_size(MPI_COMM_WORLD, &size);
> >
> > printf ("starting
> >> waiting....\n");
> >
> > if (rank == 1) {
> > //MPI_Irecv (&num, 1, MPI_INT,
> >> MPI_ANY_SOURCE, TAG,MPI_COMM_WORLD, &req);
> > //flag = 0;
> > //while (!flag){
> >> MPI_Irecv (&num, 1, MPI_INT, MPI_ANY_SOURCE, TAG,MPI_COMM_WORLD,
> >> &req);
> >> MPI_Wait (&req, &status);
> > printf ("Received: %d\n", num);
> > }
> > else if (rank
> >> == 0) {
> > num= 123;
> > scanf ("%d", &num);
> > printf ("Sending %d\n", num);
> >> MPI_Send (&num, 1, MPI_INT, 0,TAG, MPI_COMM_WORLD);
> >
> > }
> > printf ("%d is
> >> saying bye...\n", rank);
> > MPI_Finalize();
> > return
> >> 0;
> >
> > ---------------------------
> > bottom line is: im posting a receive without
> >> the sender has sent the
> > msg and it stucks... i also tried pooling the
> >> receive post with the
> > MPI_Test and also locks (the request never turn into a
> >> completed
> > one)... so, in more general words, what i want to do is a
> >> "preemptive"
> > check if there was any msg sent to this node... is there a way?
> >> cuz i
> > didnt find on the tutorials.... ty in advance
> >
> >
> >
> >
> >
> >> _______________________________________________
> > This list
> >> is archived at http://www.lam-mpi.org/MailArchives/lam/
> >
> >
> >>
> >
> >>
> >>
> >> _______________________________________________
> >> This list is archived at
> >> http://www.lam-mpi.org/MailArchives/lam/
> >>
> >>
> >
> >
> > --
> > []'s
> > Marcelo Takeshi Fukushima
> >
> > _______________________________________________
> > This list is archived at http://www.lam-mpi.org/MailArchives/lam/
> >
>
> --
> {+} Jeff Squyres
> {+} jsquyres_at_[hidden]
> {+} http://www.lam-mpi.org/
>
> _______________________________________________
> This list is archived at http://www.lam-mpi.org/MailArchives/lam/
>
--
[]'s
Marcelo Takeshi Fukushima
|
