# Failed to run example cases using openmp as backend **URL:** \ **Category:** Errors\ **Created:** [17 July 2022 13:54 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649 "2022-07-17T13:54:24Z")\ **Posts on this page:** 9\ **Page:** 2
**Author:** ![WillT](https://avatars.discourse-cdn.com/v4/letter/w/bc79bd/32.png) [@WillT](https://pyfr.discourse.group/u/WillT)\ **Post date:** [25 July 2022 07:44 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/21 "2022-07-25T07:44:58Z")
Did you try following Freddie’s advice about manually compiling libxsmm with the flags he specified? ---
**Author:** ![hwtang](https://avatars.discourse-cdn.com/v4/letter/h/a87d85/32.png) [@hwtang](https://pyfr.discourse.group/u/hwtang)\ **Post date:** [25 July 2022 09:11 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/22 "2022-07-25T09:11:38Z")
Yes. Following the install guide, I have tried to build PyFR 1.14.0 from the source code and compile every dependent package from the source code. Every package was compiled successfully. But some errors happened when I ran the cases. However, I am sorry that I did not save the error output. It should be something like “undefined symbol”. I am using a lower version of PyFR (1.12.3). When the simulation is over, I could try to reproduce the error output. ---
**Author:** ![fdw](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@fdw](https://pyfr.discourse.group/u/fdw)\ **Post date:** [25 July 2022 12:48 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/23 "2022-07-25T12:48:01Z")
This error is usually a consequence of libxsmm not being compiled with the BLAS=0 flag. Regards, Freddie. ---
**Author:** ![hwtang](https://avatars.discourse-cdn.com/v4/letter/h/a87d85/32.png) [@hwtang](https://pyfr.discourse.group/u/hwtang)\ **Post date:** [26 July 2022 02:11 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/24 "2022-07-26T02:11:07Z")
I am sure that I have added that flag. I did it in this way: ```auto git checkout 14b6cea61376653b2712e3eefa72b13c5e76e421 make STATIC=0 BLAS=0 CODE_BUF_MAXSIZE=262144 make install ``` I may try again this weekend. ---
**Author:** ![EitanA](https://avatars.discourse-cdn.com/v4/letter/e/bc79bd/32.png) [@EitanA](https://pyfr.discourse.group/u/EitanA)\ **Post date:** [28 July 2022 06:09 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/25 "2022-07-28T06:09:07Z")
I too am getting the same error when trying to run pyfr using openmp even though to the best of my understanding libxsmm has been compiled as instructed. I would be happy to understand if and what I am doing wrong. ---
**Author:** ![fdw](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@fdw](https://pyfr.discourse.group/u/fdw)\ **Post date:** [28 July 2022 11:42 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/26 "2022-07-28T11:42:11Z")
On my system: ```auto $ cd ~/Programming/libxsmm $ make -j4 SHARED=1 NOBLAS=1 $ export PYFR_XSMM_LIBRARY_PATH=$HOME/Programming/libxsmm/lib/libxsmm.so $ cd ../PyFR/examples/euler_vortex_2d $ pyfr run -bopenmp -p euler_vortex_2d.pyfrm euler_vortex_2d.ini 100.0% [====================================================================================>] 100.00/100.00 ela: 00:00:07 rem: 00:00:00 ``` with PyFR being a straight check out of v1.14 and libxsmm being the current master revision. Also verified on an Apple M1 system. Regards, Freddie. ---
**Author:** ![EitanA](https://avatars.discourse-cdn.com/v4/letter/e/bc79bd/32.png) [@EitanA](https://pyfr.discourse.group/u/EitanA)\ **Post date:** [28 July 2022 12:25 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/27 "2022-07-28T12:25:41Z")
Thank you. now it works. ---
**Author:** ![hwtang](https://avatars.discourse-cdn.com/v4/letter/h/a87d85/32.png) [@hwtang](https://pyfr.discourse.group/u/hwtang)\ **Post date:** [30 July 2022 08:28 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/28 "2022-07-30T08:28:31Z")
This way works for me, too. Thank you. However, I found a strange problem. When using openmp, the cpu usage is always nearly full, even if I only use one core ```auto pyfr run -b openmp -p inc_cylinder_2d.pyfrm inc_cylinder_2d.ini ``` (There are 24 cores on my PC, but the CPU usage was more than 90% when I used the above command.) @fdw @EitanA Did you see such a problem? ---
**Author:** ![hwtang](https://avatars.discourse-cdn.com/v4/letter/h/a87d85/32.png) [@hwtang](https://pyfr.discourse.group/u/hwtang)\ **Post date:** [30 July 2022 09:31 UTC](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649/29 "2022-07-30T09:31:39Z")
Find an answer [here](https://pyfr.discourse.group/t/running-on-a-single-cpu-core/113/2). ```auto export OMP_NUM_THREADS=1 ``` Thank you all for your help. [Previous page](https://pyfr.discourse.group/t/failed-to-run-example-cases-using-openmp-as-backend/649.md?page=1)