Hello everybody,
I spent a few hours on a little problem about sending structure. I'v got
no problem with contiguous data, like this one :
typedef struct ComputeInfo {
unsigned long long line_number ;
unsigned long long total_charge ;
} ;
which i commit with this few lines :
void Create_MPI_ULONG_LONG_PAIR(MPI::Datatype& newtype)
{
newtype = MPI::UNSIGNED_LONG_LONG.Create_contiguous(2) ;
newtype.Commit() ;
}
Now, i try to build up a MPI::Datatype based on heterogenous data. Take
this one :
typedef struct ClientStats {
double network_wait_time ;
double network_send_time ;
double compute_time ;
double start_delay ;
double total_time ;
double mhz ;
double bogomips ;
unsigned long long line_number ;
unsigned long long total_charge ;
} ;
This is the code i wrote to commit this new type :
void Create_MPI_CLIENT_STATS(MPI::Datatype& newtype)
{
// build datatype
MPI::Datatype type[2] = { MPI::DOUBLE, MPI::DOUBLE } ;
int blocklen[2] = { 7, 2 } ;
MPI::Aint disp[9] ;
ClientStats stat ;
disp[0] = MPI::Get_address(&stat.network_wait_time) ;
disp[1] = MPI::Get_address(&stat.network_send_time) ;
disp[2] = MPI::Get_address(&stat.compute_time) ;
disp[3] = MPI::Get_address(&stat.start_delay) ;
disp[4] = MPI::Get_address(&stat.total_time) ;
disp[5] = MPI::Get_address(&stat.mhz) ;
disp[6] = MPI::Get_address(&stat.bogomips) ;
disp[7] = MPI::Get_address(&stat.line_number) ;
disp[8] = MPI::Get_address(&stat.total_charge) ;
for(int i = 8; i >= 0; i--) disp[i] -= disp[0] ;
newtype = newtype.Create_struct(1, blocklen, disp, type) ;
newtype.Commit();
}
It's compile fine without any warnings, but it works quite bad. Here is
the way i use this new datatype :
// SENDER
ClientStats stat ;
[...]
MPI::COMM_WORLD.Send( &stat , 1, CLIENT_STATS, 0, TAG_STATS) ;
// RECEPTION
ClientStats stat ;
MPI::COMM_WORLD.Recv(&stat, 1, CLIENT_STATS, worker, TAG_STATS, status)
;
When i read my ClientStats structure, the unsigned long long
line_number, unsigned long long total_charge variables are unchanged,
although i send a new value.
I'm quite newbie with MPI stuff, so i think i'm doing something wrong.
It would be very nice if you can give me some advice about this problem
!
Thanx !
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