Appendix A. Tool Reference
Appendix A. Tool Reference This appendix provides a quick reference for the various tools in Red Hat Enterprise Linux 7 that can be used to tweak performance. See the relevant man page for your tool for complete, up-to-date, detailed reference material. A.1. irqbalance irqbalance is a command line tool that distributes hardware interrupts across processors to improve system performance. It runs as a daemon by default, but can be run once only with the --oneshot option. The following parameters are useful for improving performance. --powerthresh Sets the number of CPUs that can idle before a CPU is placed into powersave mode. If more CPUs than the threshold are more than 1 standard deviation below the average softirq workload and no CPUs are more than one standard deviation above the average, and have more than one irq assigned to them, a CPU is placed into powersave mode. In powersave mode, a CPU is not part of irq balancing so that it is not woken unnecessarily. --hintpolicy Determines how irq kernel affinity hinting is handled. Valid values are exact ( irq affinity hint is always applied), subset ( irq is balanced, but the assigned object is a subset of the affinity hint), or ignore ( irq affinity hint is ignored completely). --policyscript Defines the location of a script to execute for each interrupt request, with the device path and irq number passed as arguments, and a zero exit code expected by irqbalance . The script defined can specify zero or more key value pairs to guide irqbalance in managing the passed irq . The following are recognized as valid key value pairs. ban Valid values are true (exclude the passed irq from balancing) or false (perform balancing on this irq ). balance_level Allows user override of the balance level of the passed irq . By default the balance level is based on the PCI device class of the device that owns the irq . Valid values are none , package , cache , or core . numa_node Allows user override of the NUMA node that is considered local to the passed irq . If information about the local node is not specified in ACPI, devices are considered equidistant from all nodes. Valid values are integers (starting from 0) that identify a specific NUMA node, and -1 , which specifies that an irq should be considered equidistant from all nodes. --banirq The interrupt with the specified interrupt request number is added to the list of banned interrupts. You can also use the IRQBALANCE_BANNED_CPUS environment variable to specify a mask of CPUs that are ignored by irqbalance . For further details, see the man page:
man irqbalance