------- Comment From heinz-werner_se...@de.ibm.com 2020-06-26 02:48 EDT------- IBM Bugzilla status-> closed, Fix Released
-- 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: Fix Released Status in linux package in Ubuntu: Fix Released 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
