[MPICH2-dev] implementing MPID_Wtick()

[David Gingold]

Bill --

I agree that it would be cleaner just to supply our own  
implementations of those MPID functions, but I don't see how to do it  
easily within the existing structure of the MPICH2 code.  The code in  
src/mpi/timer/mpidtime.c is always built into the library (I think),  
but in our case I'd like to override that with device-specific code  
in src/mpid/sc, where our MPID implementation lives.

You see what I'm saying?  Am I missing a way to do this?

-dg

....

On Oct 10, 2007, at 2:57 PM, William Gropp wrote:

> David,
> The original thinking was that the device would provide its own  
> MPID_Wtime/MPID_Wtick implementation, overriding the default  
> implementations.  That's what I'd prefer, rather than adding yet  
> another option to configure :) .  Let us know if that won't work  
> for you.
>
> Bill
>
> On Oct 10, 2007, at 1:09 PM, David Gingold wrote:
>
>> Here is a question about implementing MPID_Wtick() in MPICH2:
>>
>> We're presently using gettimeofday() on our system to implement  
>> MPI_Wtime().  As far as I know, there is no way to ask Linux what  
>> the resolution of gettimeofday() is, but I happen to know the  
>> answer in our case: 1 microsecond.  The "generic" implementation  
>> of MPID_Wtick() tries to determine this, but now and then it  
>> returns different values for different ranks.
>>
>> To solve this, I'm inclined to add a parameter to configure.in  
>> that lets me specify, at build time, the value that MPI_Wtick()  
>> should return.  Is there a better way?  Is it expected, for  
>> example, that an ADI3 implementation might provide its own  
>> versions of the functions in src/mpid/timer/mpidtime.c, replacing  
>> or overriding what is there?
>>
>> -dg
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mcs.anl.gov/mailman/private/mpich2-dev/attachments/20071011/c857c8cf/attachment.htm>