Comment 26 for bug 1073148

Revision history for this message
Removed by request (removed3425744) wrote : Re: High cpu overhead on using multiple cores

The BIOS is now up to date:

sworddragon@ubuntu:~$ sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date
P1.40
10/02/2013

But the bug still exists on Ubuntu 14.04 dev with linux-image-generic 3.12.0.3.5. I have also updated the testcase: It is now written in C to exclude Python as the source of problems (compiling with "gcc -o threads ./threads.c -lpthread") and instead of creating 2 threads it is creating the number of online cpu cores * 2 as threads (on my processor with 6 cores 12 threads are created) as the overhead gets much higher with more threads.

Here are the results:

Calling ./test will result in a cpu usage of ~185%/600%.
Calling taskset -c 0 ./threads will result in a cpu usage of ~30%/600%.