Red Hat Bugzilla – Bug 176694
Rawhide kernel made X really slow
Last modified: 2015-01-04 17:23:56 EST
kernel-2.6.14-1.1796_FC5 kernel-2.6.14-1.1800_FC5 Something in these new kernels made everything in my X much slower. This is apparent with my GNOME multiload_applet using a constant 20-35% CPU, Xorg is busy during this, and any operation in X (minimizing, maximizing, switching windows, etc.) uses more CPU as it waits on Xorg. kernel-2.6.14-1.1786_FC5 Rebooting back into this kernel brings load back down to normal. Any idea what may have changed to make Xorg and X apps to work harder?
Hardware: IBM Thinkpad T41 Radeon 7500
kmalloc tracing. It'll be turned off in a few days. Curious its hitting you so hard though. Can you do cat /proc/kmalloc >km1 *wiggle some windows around* cat /proc/kmalloc >km2 and attach those ? I'm curious whats doing so many kernel allocations.
Created attachment 122657 [details] /proc/kmalloc before wiggling gedit window
Created attachment 122658 [details] /proc/kmalloc after wiggling gedit window
The above tests were with kernel-2.6.14-1.1800_FC5 Hmm... it seems like other things beyond X have heavy CPU usage. Simply typing in Firefox is slow and induces 100% CPU spikes. CPU maxes out for a few seconds whenever I switch windows, and it uses maybe 50% if I wiggle around a window. vpnc downloading at 100KB/sec maxed out CPU usage too. Let me know if you need any other information.
It isn't just X. The whole systems becomes 2x slower. I just recompiled the kernel from the text console, which normally takes 2 hours - it took 4! My hardware spec is here: http://www.rexursive.com/articles/linuxonhpze4201.html
bojan, can you repeat the process in comment #2 please ? Seeing different profiles from different situations may bring about some other interesting pieces of info. The interesting bits in Warren's profile I saw earlier in another report. Audit is really heavyweight. In Warrens profile, it had done nearly 40 million allocations since boot up. On my desktop it's almost constantly writing something or other to /var/log/audit. We have to make sure to turn that off by default before FC5 ships.
I did the following: rpm -ivh kernel-2.6.14-1.1796.src.rpm rpmbuild -bp --target=i686 kernel.spec The attached files show /proc/kmalloc before and after each of the commands. If you want me to do similar stuff for kernel compile, I can, but it's going to take until next year ;-) Anyhow, these two a visibly slower than before, so I think they are probably good representatives of slowness. BTW, I'm running the box with SELinux enabled (targeted) and auditd is running too. PS. You may see X springing into action here and there - that's because I was flicking between text consoles and X while doing the above and writing this comment.
Created attachment 122660 [details] Various rpm related kmalloc It appears that unpacking archives is particularly slow.
ok, thanks. I've disabled it in the current build, which will go out to rawhide tomorrow. You can grab it early at http://people.redhat.com/davej/kernels/Fedora/devel/ thanks again for the testdata.