too large local residue for mass conservation

[jdonners]

R wrote:

• test on 384^3 using ./configure FCFLAGS="-O3 -xAVX -axCORE-AVX2”. afid-1.1 crashes on an Ivy Bridge node (i.e. AVX) with the message “too large local residue for mass conservation at:”. This code works fine on a Haswell node (i.e. AVX2).
• Using only the “-O3” flag everything works well on both types of nodes.
• Using the “-O3 -xAVX” flags the code fails on both types of nodes, so the problem is in the part “-xAVX”.

It also occurs with the latest compiler version (16.0.1).

some print statements show:

...
16:  dmax,resid=  6.953275390687991E-310  1.000000000000000E-002
18:  dmax,resid=  6.952658331733957E-310  1.000000000000000E-002
00:  dmax,resid= -1.797693134862316E+308  1.000000000000000E-002
00:           too large local residue for mass conservation at:

only process 0 has a somewhat excessive residue..

the same happens with ./configure FCFLAGS="-xAVX -O0 -g -traceback", so without optimization.

[stevensrjam]

Wether the code crashes depends also on the simulation case that is configured. For 192^3 the code works also on the Ivy Bridge nodes. This problem is probably related to the one we saw for the GPU version, see Github change https://github.com/PhysicsofFluids/AFiD_GPU/commit/49dde1f3c53ac9465a107c074407ad879fd6b541

On Jan 25, 2016, at 22:38, maxcuda <notifications@github.commailto:notifications@github.com> wrote:

R wrote:

• test on 384^3 using ./configure FCFLAGS="-O3 -xAVX -axCORE-AVX2”. afid-1.1 crashes on an Ivy Bridge node (i.e. AVX) with the message “too large local residue for mass conservation at:”. This code works fine on a Haswell node (i.e. AVX2).
• Using only the “-O3” flag everything works well on both types of nodes.
• Using the “-O3 -xAVX” flags the code fails on both types of nodes, so the problem is in the part “-xAVX”.

It also occurs with the latest compiler version (16.0.1).

some print statements show:

...
16: dmax,resid= 6.953275390687991E-310 1.000000000000000E-002
18: dmax,resid= 6.952658331733957E-310 1.000000000000000E-002
00: dmax,resid= -1.797693134862316E+308 1.000000000000000E-002
00: too large local residue for mass conservation at:

only process 0 has a somewhat excessive residue..

the same happens with ./configure FCFLAGS="-xAVX -O0 -g -traceback", so without optimization.

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Reply to this email directly or view it on GitHubhttps://github.com//issues/7.

[jdonners]

the problem is that the matrix in SolvePressureCorrection becomes singular. An error message should be added with a suggestion to change either NX or STR3 in bou.in. A more general solution is not yet available.

[stevensrjam]

Added the error messages in the code. Commit 293.