MKL: cholesky decomposition error wih Xeon Phi

[Minh_H_]

Hi,

I got a simple C++ code to call lapack  dpotrf  function to do cholesky decomposition and dgetrf and  dgetri. I got very weird behavior. on  Xeon server with 6 Xeon Phi Cards

1) Performance:

For matrix size 12000x12000:

run with export  MKL_MIC_ENABLE=1 is slower than MKL_MIC_ENABLE=0:    20 seconds vs 11 seconds

It seems that MKL does not do a good job here.

2) Bug:

For cholesky decomposition: with matrix size 10000 x 10000 or 9500 x 9500 with MKL_MIC_ENABLE=1

cause "Segmentation fault (core dumped)" with kernel log:

traps: inverse[10032] general protection ip:7fc3b27955c7 sp:7fffe2da28c0 error:0 in libmkl_intel_thread.so[7fc3b206b000+ffc000]

This problem happens on MKL 11.2.1 and  11.3.0 (newest Studio 2016).

Any help please?

[Minh_H_]

Call to dpotrf using MKL on Xeon Phi sometime cause the system hang forever and and Utilization View on micsmc pannel, System about 85%? What is going on? Thanks

[Gennady_F_Intel]

The problem has been reproduced and escalated. We expect to provide the fix of the problem in the nearest update of MKL.