------- Comment From marc.beye...@de.ibm.com 2019-01-17 09:26 EDT------- Hi there, here are the answers to your questions:
- Regarding gcc versions: We are using the standard gcc versions of the distros. This is gcc 5.4.0 on Ubuntu 16.04.5 LTS and 4.8.5 on the other distros. - Regarding kernel version: We are using 4.4 kernels on both distros. Current state of our analysis: - The problem is definitely SMT-2 related. In our current setup, all SPECint2017 micro-benchmarks are running with 2 instances each. If we run them with 1 instance each, the performance is almost identical to the other major Linux distros. - The problem is related to Position Independent Executables (PIEs). If we compile the SPECint2017 micro-benchmarks with "-no-pie", the performance on Ubuntu 16.04.5 LTS is almost identical to the other major Linux distros, also when running 2 instances for each micro-benchmark. - We suspected Kernel commit a73dc5370e153ac63718d850bddf0c9aa9d871e6 to be the culprit, since this commit is related to PIEs and has been reverted by commit 345f8f34bb473241d62803951c18a844dd705f8d at a later point in time. However, newly executed test runs revealed that this commit is not causing the observed performance degradation. - We are continuing our analysis :-) Stay tuned. -- 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/1812182 Title: Performance degradation with SPECint2017 Status in Ubuntu on IBM z Systems: Incomplete Status in gcc-5 package in Ubuntu: Incomplete Status in glibc package in Ubuntu: Incomplete Status in linux package in Ubuntu: Incomplete Bug description: Problem description: During our Linux distribution performance regression testing, we found *significant* performance degradations on Ubuntu 16.04.5 LTS compared to other major Linux distributions on s390x when running SPECint2017. Some SPECint2017 micro-benchmarks show a performance degradation of 40%. Hardware environment: IBM z14, LPAR 1 IFL, SMT on 4GiB memory Software environment: Ubuntu 16.04.5 LTS SPECint2017 Analysis: We are currently in the progress of analyzing the problem and will get back to this bug as soon as we have more insights. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1812182/+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
