[Mitgcm-support] Re: idkey and multi-threading

[mitgcm-support at dev.mitgcm.org]

I don't think that's correct.
If you go to the start of dynamics.F you will see
the activation of ikey in which myThid is taken
into account and from which iikey is derived:

          act1 = bi - myBxLo(myThid)
          max1 = myBxHi(myThid) - myBxLo(myThid) + 1

          act2 = bj - myByLo(myThid)
          max2 = myByHi(myThid) - myByLo(myThid) + 1

          act3 = myThid - 1
          max3 = nTx*nTy

          act4 = ikey_dynamics - 1

          ikey = (act1 + 1) + act2*max1
     &                      + act3*max1*max2
     &                      + act4*max1*max2*max3

Patrick

Chris Hill wrote:
> 
> I was doing some work with Veronique and noticed the
> the idkey mechanism that is used to control which
> block of storage TAMC will work with in IMPLDIFF.
> This mechanism will not work in a multi-threaded code.
> All threads see the same idkey, even though each thread may
> not be at the same instance of impldiff.
> 
>         IF (implicitViscosity.AND.momStepping) THEN
> #ifdef    ALLOW_AUTODIFF_TAMC
>           idkey = iikey + 3
> #endif    /* ALLOW_AUTODIFF_TAMC */
>           CALL IMPLDIFF(
>      I         bi, bj, iMin, iMax, jMin, jMax,
>      I         deltaTmom, KappaRU,recip_HFacW,
>      U         gUNm1,
>      I         myThid )

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Patrick Heimbach                        FON: +1 / 617 / 253-5259
Massachusetts Institute of Technology   FAX: +1 / 617 / 253-4464 
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