function::set_kernel_long - Linux


The function::set_kernel_long sets a kernel function parameter to a 64-bit integer value. This command is used to fine-tune the behavior of various Linux kernel functions and modules, allowing for advanced customization and optimization.


function::set_kernel_long <function_name> <parameter_name> <64-bit_integer_value>




Example 1: Set the Maximum Retries for a SCSI Disk

function::set_kernel_long scsi_disk_max_retries 4

This command sets the maximum number of retries for SCSI disk operations to 4, potentially improving performance for unreliable storage devices.

Example 2: Adjust the Size of TCP Send Buffer

function::set_kernel_long tcp_wmem 12582912

This command increases the TCP send buffer size to 12 MB, potentially reducing latency and improving throughput for network transfers.

Common Issues

  • Invalid Function Name: Ensure that the specified function name corresponds to a valid kernel function that accepts a 64-bit integer parameter.
  • Invalid Parameter: Verify that the parameter name is correct and refers to a valid parameter within the kernel function.
  • Permission Errors: The command may require root privileges to access and modify kernel parameters.


The function::set_kernel_long command can be combined with other tools for advanced system administration tasks:

  • sysctl: To perform temporary changes to kernel parameters, e.g. sysctl -w function::set_kernel_long.fiber 1.
  • Bash Scripting: Embed the command into scripts for automated configuration or performance tuning.

Related Commands

  • sysctl – Set and display kernel parameters.
  • proc – Inspect kernel and system information.
  • dmesg – Display kernel boot messages.