Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.15 kernel[0].
If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'. If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'. If you are unable to test the mainline kernel, for example it will not boot, please add the tag: 'kernel-unable-to-test-upstream'. Once testing of the upstream kernel is complete, please mark this bug as "Confirmed". Thanks in advance. [0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.15-rc4-utopic/ ** Changed in: linux (Ubuntu) Importance: Undecided => Medium ** Changed in: linux (Ubuntu) Status: Confirmed => Incomplete ** Tags added: kernel-da-key precise -- 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/1315619 Title: Job with 4 threads not assigned 4 distinct cores Status in “linux” package in Ubuntu: Incomplete Bug description: On 12.04, I have reliably found that a job which starts 4 long-running threads on an otherwise-idle machine (there are some other threads which have been running for some time, but they have been kill -STOPped) gets the threads allocated to 4 distinct cores on my Haswell. On 14.04, I found that the threads were allocated to cores 0, 1, 5, 6 - that is, two were running on the two hyper-threads 1 and 5 of the same core, and performance was 30% less than expected. I can get around this with explicit taskset commands, but for my use case it's a serious regression from 12.04. I am not willing to disable hyperthreading, because it gives a large performance boost on other things I do on the same machine. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1315619/+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
