# Loss of performance in v. 2021 **URL:** \ **Category:** User discussions\ **Tags:** mdrun\ **Created:** [December 17, 2021, 8:04am UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323 "2021-12-17T08:04:55Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![pszilard](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/pszilard/32/21_2.png) [@pszilard](https://gromacs.bioexcel.eu/u/pszilard)\ **Post date:** [January 19, 2022, 2:23pm UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323/21 "2022-01-19T14:23:58Z")
Unfortunately with vsites GPU-resident mode (where integration is on the GPU) is not supported, so try removing `-udpate gpu` (or pass `-update cpu`). ---
**Author:** ![Sasha](https://avatars.discourse-cdn.com/v4/letter/s/54ee81/32.png) [@Sasha](https://gromacs.bioexcel.eu/u/Sasha)\ **Post date:** [January 19, 2022, 10:22pm UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323/22 "2022-01-19T22:22:31Z")
With -update cpu, the results are in. `gmx mdrun -ntmpi 1 -ntomp 24 -bonded gpu -pme gpu` 351.4 ns/day `gmx mdrun -ntmpi 2 -npme 1 -ntomp 23 -ntomp_pme 1 -bonded gpu -pme gpu` 429.4 ns/day – I did set the env vars as instructed within the submission script. These numbers are to be compared with the 2 fs timestep data I posted before (nearly 600 ns/day), so my 4-GPU runs are still winning. :) ---
**Author:** ![pszilard](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/pszilard/32/21_2.png) [@pszilard](https://gromacs.bioexcel.eu/u/pszilard)\ **Post date:** [January 20, 2022, 1:08pm UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323/23 "2022-01-20T13:08:45Z")
Interesting, thanks for testing. One last check you could do is using three of the four GPUs. Are you able to share you input, I’d like to have such a case as a reference. We will soon have the release candidate of the 2022 release out which contains multiple multi-GPU improvements. It would be great if you could test it and give feedback on the new release. ---
**Author:** ![Sasha](https://avatars.discourse-cdn.com/v4/letter/s/54ee81/32.png) [@Sasha](https://gromacs.bioexcel.eu/u/Sasha)\ **Post date:** [January 20, 2022, 10:31pm UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323/24 "2022-01-20T22:31:59Z")
I think I tested on 3 GPUs earlier – don’t remember the exact performance, but it was scaling as well. Happy to share the input privately, if you could provide an email address you prefer, because it looks like there’s no way to send a private message to you here. ---
**Author:** ![pszilard](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/pszilard/32/21_2.png) [@pszilard](https://gromacs.bioexcel.eu/u/pszilard)\ **Post date:** [January 28, 2022, 10:12am UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323/25 "2022-01-28T10:12:44Z")
You can send private messages here, e.g. by clicking on the icon next to the post and selecting “Message”: ![image](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/c/c5ae8a04e2460cc1cc0097d47d4c9d8e97e06bcc.png) ---
**Author:** ![Sasha](https://avatars.discourse-cdn.com/v4/letter/s/54ee81/32.png) [@Sasha](https://gromacs.bioexcel.eu/u/Sasha)\ **Post date:** [January 28, 2022, 10:38am UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323/26 "2022-01-28T10:38:04Z")
Nope. Same thing with other users that don’t have hidden profiles. Maybe send me one and hopefully I can reply. ![Screenshot 2022-01-28 033547](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/8/8c6323bec900c3a3605a4fd7cea239dd283b4cff.png) ---
**Author:** ![Yel21](https://avatars.discourse-cdn.com/v4/letter/y/b2d939/32.png) [@Yel21](https://gromacs.bioexcel.eu/u/Yel21)\ **Post date:** [August 23, 2026, 8:12am UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323/27 "2026-08-23T08:12:15Z")
Dear Gromacs developers, Perhaps there is an option to speed up simulations of water models TIP4P and OPC using GPU acceleration `-update gpu`? Best regards, Victor ---
**Author:** ![hess](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/hess/32/416_2.png) [@hess](https://gromacs.bioexcel.eu/u/hess)\ **Post date:** [August 24, 2026, 8:43am UTC](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323/28 "2026-08-24T08:43:13Z")
This is currently not supported, but is will be added in version 2027. This can result in a significant speed-up. [Previous page](https://gromacs.bioexcel.eu/t/loss-of-performance-in-v-2021/3323.md?page=1)