July 10, 2020 at 8:54 pmhelen.durandSubscriber
Hello ANSYS forums,
I am currently running a Workbench simulation with Fluent on a HPC cluster, and I have been receiving the following warning when opening Fluent.
WARNING: Rank: 0 Machine wsu182 has 79% of RAM filled with file buffer caches
This can cause potential performance issues. Please use -cflush flag to flush the cache.
Does someone have any insight into what this means exactly?
I know that the nodes are being shared among many users. When it says that 79% of RAM is filled, is it referring to 79% of the RAM on the entire node, or is it referring to 79% of the RAM allotted to my simulation?
Also, I was unable to figure out how to use the -cflush command.
I noticed that another user has previously posed a similar question that has not been answered (see: https://studentcommunity.ansys.com/thread/running-fluent-on-cluster-clear-node-cache/?order=all#comment-4328dd1e-45ec-4734-b16a-ab9500ea4ba8).
Thank you for taking the time to look into this.
July 13, 2020 at 12:43 pmKarthik RAdministrator
The warning message is saying that the OS is not, by default, freeing up the file cache buffer immediately even after the Fluent session exits.
This would need manual intervention. Please make sure that the machines are idle and no jobs are running on the machine. Otherwise, running jobs are adversely impacted.
Please try these following instructions. It is best if your IT handles these. They should be able to script this.
You should be able to drop cache via “/sbin/sysctl vm.drop_caches=3”
This option requires “sudo” privilege for setting /sbin/sysctl vm.drop_caches=3.
This option is instantaneous.
This option can be invoked via scheme command as shown below two examples. You can choose any one of them as per your convenience. o (%node-run -1 "sudo /sbin/sysctl vm.drop_caches=3")
I hope this helps.
- You must be logged in to reply to this topic.
Simulation World 2022
Check out more than 70 different sessions now available on demand. Get inspired as you hear from visionary companies, leading researchers and educators from around the globe on a variety of topics from life-saving improvements in healthcare, to bold new realities of space travel. Take a leap of certainty and check out a session today here.
Earth Rescue – An Ansys Online Series
The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.
Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.
- Suppress Fluent to open with GUI while performing in journal file
- Heat transfer coefficient
- What are the differences between CFX and Fluent?
- Floating point exception in Fluent
- The solver failed with a non-zero exit code of : 2
- Getting graph and tabular data from result in workbench mechanical
- Difference between K-epsilon and K-omega Turbulence Model
- Time Step Size and Courant Number
- Mesh Interfaces in ANSYS FLUENT
- error in cfd post
© 2022 Copyright ANSYS, Inc. All rights reserved.