Using qperf to measure network bandwidth and latency

qperf is a network bandwidth and latency measurement tool which works over many transports including TCP/IP, RDMA, UDP and SCTP

Step 1: Installing qperf on both Server and Client

Server> # yum install qperf
Client> # yum install qperf

Step 2: Open Up the Firewall on the Server

# firewall-cmd --permanent --add-port=19765-19766/tcp
# firewall-cmd --reload

The Server listens at TCP Port 19765 by default. Do note that once qperf makes a connection, it will create a control port and data port , the default data port is 19765 but we also need to enable a data port to run test which can be 19766.

Step 3a: Have the Server listen (as qperf server)

Server> $ qperf

Step 4: Connect to qperf Server with qperf Client and measure bandwidth

Client > $ qperf -ip 19766 -t 60 qperf_server_ip_address tcp_bw
    bw  =  2.52 GB/sec

Step 5: Connect to qperf Server with qperf Client and measure latency

qperf -vvs qperf_server_ip_address tcp_lat
latency = 20.7 us
msg_rate = 48.1 K/sec
loc_send_bytes = 48.2 KB
loc_recv_bytes = 48.2 KB
loc_send_msgs = 48,196
loc_recv_msgs = 48,196
rem_send_bytes = 48.2 KB
rem_recv_bytes = 48.2 KB
rem_send_msgs = 48,197
rem_recv_msgs = 48,197


  1. How to use qperf to measure network bandwidth and latency performance?

How to configure NFS on CentOS 7

Step 1: Do a Yum Install

# yum install nfs-utils rpcbind

Step 2: Enable the Service at Boot Time

# systemctl enable nfs-server
# systemctl enable rpcbind
# systemctl enable nfs-lock     (it does not need to be enabled since rpc-statd.service  is static.)
# systemctl enable nfs-idmap    (it does not need to be enabled since nfs-idmapd.service is static.)

Step 3: Start the Services

# systemctl start rpcbind
# systemctl start nfs-server
# systemctl start nfs-lock
# systemctl start nfs-idmap

Step 4: Confirm the status of NFS

# systemctl status nfs

Step 5: Create a mount point

# mkdir /shared-data

Step 6: Exports the Share

# vim /etc/exports

Step 7: Export the Share

# exportfs -rv

Step 8: Restart the NFS Services

# systemctl restart nfs-server

Step 9: Configure the Firewall

# firewall-cmd --add-service=nfs --zone=internal --permanent
# firewall-cmd --add-service=mountd --zone=internal --permanent
# firewall-cmd --add-service=rpc-bind --zone=internal --permanent


  1. How to configure NFS in RHEL 7
  2. What firewalld services should be active on an NFS server in RHEL 7?

Performance Required for Deep Learning

There is this question that I wanted to find out about deep learning. What are essential System, Network, Protocol that will speed up the Training and/or Inferencing. There may not be necessary to employ the same level of requirements from Training to Inferencing and Vice Versa. I have received this information during a Nvidia Presentation


  1. Scalability requires ultra-fast networking
  2. Same hardware needs as HPC
  3. Extreme network bandwidth
  4. RDMA
  5. SHARP (Mellanox Scalable Hierarchical Aggregation and Reduction Protocol)
  6. GPUDirect (
  7. Fast Access Storage


  1. Highly Transactional
  2. Ultra-low Latency
  3. Instant Network Response
  4. RDMA
  5. PeerDirect, GPUDirect



Configuring External libraries for R-Studio for CentOS 7

RStudio can be configured by adding entries to 2 configuration files. It may not exist by default and you may need to create


If you need to add additional libraries to the default LD_LIBRARY_PATH for R sessions. You have to add the parameters to the /etc/rstudio/rserver.conf

Step 1: Enter External Libraries settings
For example, you may want to add GCC-6.5 libraries

# Server Configuration File

Step 2a: Stop the R Server Services

# /usr/sbin/rstudio-server stop

Step 2b: Verify the Installation

# rstudio-server verify-installation

Step 2c: Start the R Server Services

# /usr/sbin/rstudio-server start
# /usr/sbin/rstudio-server status

(Make sure there is no error)


  1. RStudio Server: Configuring the Server


AlmaLinux Enterprise-Grade Server OS compatible with RHEL 8

What is AlmaLinux? According to the website

AlmaLinux is an enterprise-grade server OS, a stable Linux distribution with regular releases that come with long support windows. You can rely on AlmaLinux to run you and your clients’ critical workloads.

  • Fedora-like distribution based on a precise RHEL clone
  • Production-ready and stable, matching RHEL features 1:1
  • Enjoy the predictability of a stable release issued in tandem with RHEL

No-Cost, Self-Supported RHEL up to 16 systems under Individual Developer Subscription for RHEL

From RHEL, “No-cost RHEL for small production workloads and customer development teams

We’re addressing this by expanding the terms of the Red Hat Developer program so that the Individual Developer subscription for RHEL can be
used in production for up to 16 systems. That’s exactly what it sounds like: for small production use cases, this is no-cost, self-supported RHEL.
You need only to sign in with a free Red Hat account (or via single sign-on through GitHub, Twitter, Facebook, and other accounts) to download
RHEL and receive updates. Nothing else is required. This isn’t a sales program and no sales representative will follow up. An option will exist within
the subscription to easily upgrade to full support, but that’s up to you.


The updated Individual Developer subscription for RHEL will be available no later than February 1, 2021.