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Updated irqbalance packages that fix several bugs are now available for Red Hat Enterprise Linux 6.
The irqbalance packages provide a daemon that evenly distributes the interrupt request (IRQ) load across multiple CPUs for enhanced performance.
- Previously, the irqbalance daemon did not consider the NUMA node assignment for an interrupt request (IRQ) for the banned CPU set. Consequently, irqbalance set the affinity incorrectly when the IRQBALANCE_BANNED_IRQS variable was set to a single CPU. In addition, IRQs could be assigned to a node that had no eligible CPUs. Node assignment has been restricted to nodes that have eligible CPUs as defined by the unbanned_cpus bitmask, thus fixing the bug. As a result, irqbalance now sets the affinity properly, and IRQs are assigned to the respective nodes correctly.
- Prior to this update, the dependency of the irqbalance daemon was set incorrectly referring to a wrong kernel version. As a consequence, irqbalance could not balance IRQs on NUMA systems. With this update, the dependency has been fixed, and IRQs are now balanced correctly on NUMA systems. Note that users of irqbalance packages have to update the kernel to 2.6.32-358.2.1 or later in order to use the irqbalance daemon in the correct manner.
- Prior to this update, irqbalance could not accurately determine the NUMA node it was local to or the device to which an IRQ was sent. The kernel affinity_hint values were created to work around this issue. With this update, irqbalance is now capable of parsing all information about an IRQ provided by the sysfs() function. IRQ balancing now works correctly, and the affinity_hint values are now ignored by default not to distort the irqbalance functionality.
Users of irqbalance are advised to upgrade to these updated packages, which fix these bugs.