[MPICH2-dev] implementing MPID_Wtick()

[William Gropp]

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
>
> --
> David Gingold
> Principal Software Engineer
> SiCortex
> Three Clock Tower Place, Suite 210
> Maynard MA 01754
> (978) 897-0214 x224
>
>
>

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