Indicates the kernel parameters that you need to tune for enhanced system
performance.
Tune the following kernel parameters to enhance system performance.
- fs.aio-max-nr
- Preferred Value: 262144
- Purpose: Enhances throughput. Tunes the Asynchronous non-blocking I/O (AIO)
feature that allows a process to initiate multiple I/O operations simultaneously without
having to wait for any of them to complete. This helps boost performance for applications
that are able to overlap processing and I/O.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: No
- Applicable to Containerized Client: No
- fs.epoll.max_user_watches
- Preferred Value: 32768
- Purpose: Enhances throughput for high memory/CPU machines. Specifies a limit on
the total number of file descriptors that a user can register across all epoll instances
on the system. The limit is per real user ID.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- fs.file-max
- Preferred Value: 32768
- Purpose: Enhances throughput for high memory/CPU machines. Tunes the number of
concurrently open file descriptors on the system.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.ipv4.route.flush
- Preferred Value: 1
- Purpose: Makes the TCP configurations effective instantly.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.core.rmem_max
- Preferred Value: 4194304
- Purpose: Enhances throughput by tuning the TCP stack. Sets the maximum OS receive
buffer size for all types of connections.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.core.rmem_default
- Preferred Value: 1048576
- Purpose: Enhances throughput by tuning the TCP stack. Sets the default OS receive
buffer size for all types of connections.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.core.wmem_max
- Preferred Value: 4194304
- Purpose: Enhances throughput by tuning the TCP stack. Sets the maximum OS send
buffer size for all types of connections.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.core.wmem_default
- Preferred Value: 1048576
- Purpose: Enhances throughput by tuning the TCP stack. Sets the default OS send
buffer size for all types of connections.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.core.netdev_max_backlog
- Preferred Value: 30000
- Purpose: Enhances throughput by tuning the TCP stack. Sets the maximum number of
packets, queued on the INPUT side, when the interface receives packets faster than kernel
can process them.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.ipv4.tcp_rmem
- Preferred Value: 4096 1048576 4194304
- Purpose: Enhances throughput by tuning the TCP stack. Increase the read-buffer
space allocatable (minimum size, initial size, and maximum size in bytes).
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.ipv4.tcp_wmem
- Preferred Value: 4096 1048576 4194304
- Purpose: Enhances throughput by tuning the TCP stack. Increase the write-buffer
space allocatable (minimum size, initial size, and maximum size in bytes).
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.ipv4.tcp_mem
- Preferred Value: 8388608 8388608 8388608
- Purpose: Enhances throughput by tuning the TCP stack. Increase the maximum total
buffer-space allocatable ((minimum size, initial size, and maximum size in pages (4096
bytes each)).
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.ipv4.tcp_syn_retries
- Preferred Value: 4
- Purpose: Maintains High Availability by detecting failures rapidly. This is a TCP
setting that ensures that the TCP stack takes about 30 seconds to detect failure of a
remote node. Note that this is a setting that impacts all TCP connections. Hence, exercise
caution in lowering this further.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- net.ipv4.tcp_retries2
- Preferred Value: 5
- Purpose: Maintains High Availability by detecting failures rapidly. Influences
the timeout of a TCP connection that is alive, when RTO retransmissions remain
unacknowledged. Given a value of N, a hypothetical TCP connection following exponential
backoff with an initial RTO of TCP_RTO_MIN would retransmit N times before killing the
connection at the (N+1)th RTO.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- vm.dirty_ratio
- Preferred Value: 6
- Purpose: Maintains High Availability by guaranteeing fast resync time. Denotes
the absolute amount of system memory which when dirty, the process doing writes would
block and write out dirty pages to the disks.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- vm.dirty_background_ratio
- Preferred Value: 3
- Purpose: Maintains High Availability by guaranteeing fast resync time. Denotes
the percentage of system memory that can be filled with dirty pages — memory pages that
still need to be written to disk — before being written to disk.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- vm.overcommit_memory
- Preferred Value: 0
- Purpose: Enhances throughput. Allows the system to heuristically manage memory
rather than overcommiting and experiencing crashes when memory is exhausted.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes
- vm.swappiness
- Preferred Value: 1
- Purpose: Enhances throughput. A value of 1 means start using swap only when 99%
of RAM is utilized. This is not required if the containers do not have swap.
- Applicable to MFS (Bare Metal or Containerized): Yes, if containerized MFS uses
swap space.
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes, if container uses swap space.
- max_sectors_kb
- Preferred Value: 1024
- Purpose: Enhances throughput. Sets the maximum I/O per block disk. For
example:
echo "1024" > /sys/block/$devName/queue/max_sectors_kb
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: No
- Applicable to Containerized Client: No
- scheduler
- Preferred Value: noop
- Purpose: Enhances throughput. NOOP is the simplest I/O scheduler for the Linux
kernel based upon the FIFO queue concept. The NOOP scheduler inserts all incoming I/O
requests into a simple FIFO queue and implements request merging. The scheduler assumes
that I/O performance optimization will be handled at some other layer of the I/O
hierarchy. Set NOOP per disk controller. For example:
echo noop > /sys/block/hda/queue/scheduler
NOTE
For a high performance SSD on RHEL 8.x, it is recommended to set
the scheduler to
none or
kyber, as
explained.
- Applicable to Bare Metal Client: No
- Applicable to Containerized Client: No
- core-pattern
- Preferred Value:
/opt/cores/%e.core.%p.%h
- Purpose: Enhances supportability. Indicates where and what should be the core
file name in case a process crashes.
- Applicable to MFS (Bare Metal or Containerized): Yes
- Applicable to Bare Metal Client: Yes
- Applicable to Containerized Client: Yes