------- Comment From [email protected] 2019-11-26 10:31 EDT------- (In reply to comment #6) > Since I see 1910 as targetmilestone in the tags I assume that issue occured > on disco's kernel 5.0. > But please can you let us know is bionic' 4.15 is affected, too - or > Eoan/5.3 and higher? > Thx
4.15 as well as every higher kernel level is affected. -- 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/1854059 Title: [UBUNTU] kernel: cpu idle time calculation Status in Ubuntu on IBM z Systems: Incomplete Status in linux package in Ubuntu: Incomplete Bug description: Description: kernel: cpu idle time calculation Symptom: The cpu idle time reported within /proc/stat as well as in /sys/devices/system/cpu/cpuX/idle_time_us sometimes may show incorrect values. Problem: The kernel tries to figure out when a cpu entered idle by accessing its per-cpu data structure. There is an ordering problem: if a remote cpu has an idle_enter value which is not zero, and an idle_exit value which is zero, it is assumed it is idle since "now". The "now" timestamp however is taken before the idle_enter value is read. This in turn means that "now" can be smaller than idle_enter of the remote cpu. Unconditionally subtracting idle_enter from "now" can thus lead to a negative value (aka large unsigned value). Solution: Move the get_tod_clock() invocation. Upstream-ID: https://github.com/torvalds/linux/commit/3d7efa4edd07be5c5c3ffa95ba63e97e070e1f3f Patch tagged as "stable". Tracking the integration of this patch in the relevant distros.. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1854059/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
