** Description changed: [Impact] The LTP cpuset_sched_domains test, authored by Miao Xie, fails on a Kunpeng920 server that has 4 NUMA nodes: - https://launchpad.net/bugs/1951289 + https://launchpad.net/bugs/1951289 This does appear to be a real bug. /proc/schedstat displays 4 domain levels for CPUs on 2 of the nodes, but only 3 levels for the others 2 (see below). I assume this means the scheduler is making suboptimal decisions about where to place/move processes. [Test Case] On a 128 core Kunpeng 920 system, observe that half the CPUs are missing a 3rd level scheduling domain: ubuntu@d06-4:~$ grep domain2 /proc/schedstat | wc -l 128 ubuntu@d06-4:~$ grep domain3 /proc/schedstat | wc -l 64 - ubuntu@d06-4:~$ + ubuntu@d06-4:~$ [What Could Go Wrong] - This changes the code used for populating sched domains, so it could potentially break on other systems, potentially leading to poor scheduling characteristics (higher latencies, lower overall throughput etc). + This changes the code used for populating sched domains, so it could potentially break on other systems, leading to poor scheduling characteristics (higher latencies, lower overall throughput etc).
-- 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/1951289 Title: ubuntu_ltp_controllers:cpuset_sched_domains: tests 3,9,11,17,19,25 report incorrect sched domain for cpu#32 Status in kunpeng920: In Progress Status in kunpeng920 ubuntu-18.04 series: In Progress Status in kunpeng920 ubuntu-18.04-hwe series: Fix Committed Status in kunpeng920 ubuntu-20.04 series: Fix Committed Status in kunpeng920 upstream-kernel series: Fix Released Status in ubuntu-kernel-tests: Invalid Status in linux package in Ubuntu: Fix Released Status in linux source package in Bionic: Fix Committed Status in linux source package in Focal: Fix Committed Status in linux source package in Hirsute: Won't Fix Bug description: [Impact] The LTP cpuset_sched_domains test, authored by Miao Xie, fails on a Kunpeng920 server that has 4 NUMA nodes: https://launchpad.net/bugs/1951289 This does appear to be a real bug. /proc/schedstat displays 4 domain levels for CPUs on 2 of the nodes, but only 3 levels for the others 2 (see below). I assume this means the scheduler is making suboptimal decisions about where to place/move processes. [Test Case] On a 128 core Kunpeng 920 system, observe that half the CPUs are missing a 3rd level scheduling domain: ubuntu@d06-4:~$ grep domain2 /proc/schedstat | wc -l 128 ubuntu@d06-4:~$ grep domain3 /proc/schedstat | wc -l 64 ubuntu@d06-4:~$ [What Could Go Wrong] This changes the code used for populating sched domains, so it could potentially break on other systems, leading to poor scheduling characteristics (higher latencies, lower overall throughput etc). To manage notifications about this bug go to: https://bugs.launchpad.net/kunpeng920/+bug/1951289/+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
