Red Hat Bugzilla – Bug 128427
kernel 2.6.6 1.5 times slower than 2.4.22 in cpu intensive programs
Last modified: 2015-01-04 17:08:10 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040510 Description of problem: A cpu intensive application running on fedora 2 using kernel 2.6.6 is 1.5 times slower than on fedora 1 using kernel 2.4.22. The application is a computational fluid dynamics fortran code compiled using either ifort or g77. The machine is a centrino 1.4 GHz (thinkpad t41 2373-2fg) with 768MB RAM. No swap was observed during tests on both installations. Version-Release number of selected component (if applicable): kernel 2.6.6 How reproducible: Always Steps to Reproduce: 1.compile 2.execute 3.get time Expected Results: Additional info: I've saw some posts about 2.6 beeing slower than 2.4 but not 1.5 times slower.
We are unlikely to be able to investigate why you see this behavior unless you can post a freely distributable test suite that exhibits this problem. Only then would developers be able to profile it and see what the cause is.
After some tests I found that if I run the program outside the X environment, using init 3 on the startup, there is no significant difference between kernels. So, my complain is not correct and this seems more a question about fedora 2/fedora 1 and X environment. What makes me believe that was a kernel problem was the fact that a 2.4.22 kernel that I force into fedora 2 enabled the code running 1.5 times faster, recovering the performance that I use to have in fedora 1. For my this bug is closed Thanks
mass update for old bugs: Is this still a problem with the 2.6.9 based update kernel ?