Public bug reported: On a machine with one i7-4930K CPU (six cores; twelve threads), I run
apt-get install gmp-ecm echo 417851657851322288874010837856502301110211653321414464007924033448506685217369529551512221034931058157509867474898886146419540545861923501516226812207 > N for u in $(seq 1 12); do ecm -c 200 1e8 < N > e$u & done Expected behaviour: * good interactive response from machine * load average around 12.0 * twelve jobs appear in top, each with about 100% of a thread * mpstat -P ALL 1 displays a job running at 100% on each of the twelve CPUs Actual behaviour: * lousy interactive response from machine: pumpkin@pumpkin:/home/nfsworld/aliquot/2360.1573/e$ time ls / bin boot core dev etc home initrd.img initrd.img.old lib lib32 lib64 lost+found media mnt oldroot opt proc root run sbin srv sys tmp usr var vmlinuz vmlinuz.old real 0m53.205s * load average is somewhere around seven * somewhere between four and six jobs appear in top, with many using much less than 100% of a thread PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 5362 pumpkin 20 0 513756 504388 2912 R 100.0 1.5 1:54.28 ecm 5363 pumpkin 20 0 12552 2380 2224 R 100.0 0.0 1:32.32 ecm 5366 pumpkin 20 0 513692 503932 2832 R 100.0 1.5 0:40.80 ecm 5367 pumpkin 20 0 513752 504416 2940 R 93.2 1.5 2:32.51 ecm 5368 pumpkin 20 0 12596 3152 2836 R 16.2 0.0 6:00.99 ecm 5370 pumpkin 20 0 12596 3116 2800 R 9.9 0.0 6:31.30 ecm * mpstat -P ALL 1 indicates several idle CPUs 18:26:46 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 18:26:47 all 50.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 49.96 18:26:47 0 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 18:26:47 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 18:26:47 2 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 18:26:47 3 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 18:26:47 4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 18:26:47 5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 18:26:47 6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 18:26:47 7 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 18:26:47 8 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 18:26:47 9 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 18:26:47 10 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 18:26:47 11 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 This makes the machine pretty much unusable as a compute workstation, which is what I was using it for pre-upgrade. Please advise. ** Affects: ubuntu Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1516289 Title: scheduling of multiple CPU-intense applications is wrong To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1516289/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs