** Tags removed: performance ** Tags added: regression-release -- 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/1388276
Title: 14.10 about 2 to 3 times slower to perform concurrent tasks Status in “linux” package in Ubuntu: Incomplete Bug description: I've just upgraded two servers to use 14.10 (they were before at 14.04) and found that my builds were taking much longer: - A jenkins regression test suite that took about 135 minutes is now taking about 300 minutes. - A C complation tasks which took the following amount of time (time from tcsh): 419.633u 9.471s 1:36.78 443.3% 0+0k 0+166968io 0pf+0w is now taking 519.637u 11.022s 4:42.80 187.6% 0+0k 0+176216io 0pf+0w Both tasks are heavily using all the available cores of the processor. In one case it is a dual socket E5420 ( 8 cores), in another case it is a virtualized 8 cores E5645. I first thought it could be the new version of gcc (4.9) since both tasks involves a lot of C compilation. Although gcc 4.9 is slower (3s vs 2.8s in my own tests) it is not enough to explain the difference. I actually also tried using gcc 4.8 and 4.7 with the same performance degradation. I unfortunately do not have a 14.04 server to which I can compare the results to see where the difference is in terms of performance. Is anyone observing the same behavior? To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1388276/+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
