# GMX\_USE\_RDTSCP=ON CMake option
**URL:** https://gromacs.bioexcel.eu/t/gmx-use-rdtscp-on-cmake-option/1026
**Category:** User discussions
**Created:** [October 31, 2020, 3:36pm UTC](https://gromacs.bioexcel.eu/t/gmx-use-rdtscp-on-cmake-option/1026 "2020-10-31T15:36:08Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@abass](https://gromacs.bioexcel.eu/u/abass)
#### Post date: [October 31, 2020, 3:36pm UTC](https://gromacs.bioexcel.eu/t/gmx-use-rdtscp-on-cmake-option/1026/1 "2020-10-31T15:36:08Z")
GROMACS version: 2018.1
GROMACS modification: Yes/No
Here post your question
_The current CPU can measure timings more accurately than the code in_ \> _gmx was configured to use. This might affect your simulation_ \> _speed as accurate timings are needed for load-balancing._ \> _ **Please consider rebuilding gmx with the GMX\_USE\_RDTSCP=ON CMake option**._
please who can make solve this problem?
i need help badly?
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### Author:  [@S.Z](https://gromacs.bioexcel.eu/u/S.Z)
#### Post date: [October 31, 2020, 10:52pm UTC](https://gromacs.bioexcel.eu/t/gmx-use-rdtscp-on-cmake-option/1026/2 "2020-10-31T22:52:50Z")
This is not really a problem but rather is a suggestion so that enabling the low level timing instruction would give you a better performance.
To do so, your should recompile the Gromacs having the GMX\_USE\_RDTSCP = ON in CMake step.
If I am not entirely wrong, it should be by default enabled if the Gromacs is compiled with enabled SIMD acceleration (DGMX\_SIMD = xxx likes AVX2\_256).
Cheers,
Salman Zarrini
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### Author:  [@abass](https://gromacs.bioexcel.eu/u/abass)
#### Post date: [November 1, 2020, 5:36am UTC](https://gromacs.bioexcel.eu/t/gmx-use-rdtscp-on-cmake-option/1026/3 "2020-11-01T05:36:25Z")
please how can I recompile?
What are the steps involve?
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### Author:  [@S.Z](https://gromacs.bioexcel.eu/u/S.Z)
#### Post date: [November 2, 2020, 12:41am UTC](https://gromacs.bioexcel.eu/t/gmx-use-rdtscp-on-cmake-option/1026/4 "2020-11-02T00:41:36Z")
> **[Installation guide — GROMACS 2020.4 documentation](http://manual.gromacs.org/documentation/current/install-guide/index.html)**
Good luck
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### Author:  [@RAms](https://gromacs.bioexcel.eu/u/RAms)
#### Post date: [November 3, 2020, 8:54pm UTC](https://gromacs.bioexcel.eu/t/gmx-use-rdtscp-on-cmake-option/1026/5 "2020-11-03T20:54:25Z")
while you are in your build directory.
use
> cmake … -DGMX\_USE\_RDTSCP=ON -DGMX\_SIMD= _/Pick the ideal SIMD option for your CPU from the installation guide/_
> (It is a double dot after cmake command, idk why it is formatting double dot as triple)
you can add more options(e.g double precision, gpu and cuda support) simply by visiting here and pick the best which suits your needs
[http://manual.gromacs.org/documentation/current/install-guide/index.html](http://manual.gromacs.org/documentation/current/install-guide/index.html)