The commit: s390/pci: do not set affinity for floating irqs 86dbf32da150339ca81509fa2eb84c814b55258b
will be picked up based on the following upstream release update: Focal update: v5.4.37 upstream stable release: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1876765 Aligning this status and setting it to In Progress. ** Changed in: linux (Ubuntu) Status: New => In Progress ** Changed in: ubuntu-z-systems Status: Triaged => In Progress ** Changed in: ubuntu-z-systems Assignee: (unassigned) => Skipper Bug Screeners (skipper-screen-team) -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1874062 Title: [UBUNTU 20.04] Performance floating interrupt Status in Ubuntu on IBM z Systems: In Progress Status in linux package in Ubuntu: In Progress Bug description: With the introduction of CPU directed interrupts the kernel parameter pci=force_floating was introduced to fall back to the previous behavior using floating irqs. Furthermore this fallback is used on machines lacking support for directed interrupts. However we were still setting the affinity in that case, both in __irq_alloc_descs() and via the irq_set_affinity callback in struct irq_chip. This setting of the affinity leads to a performance regression in streaming workloads which can be seen with e.g. by an iperf streaming test between two LPARs using ConnectX-5 based nics. In some tests the performance would drop to 20% of the performance with older kernels. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1874062/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
