Same problem on a HP Pavilion dv6415eb (Intel based) using Ubuntu 9.04. After many research, kernel compiles and querying the advice of Vincent Minder I found what seems the base of the problem. Any Linux install (Ubuntu, Slackware, Fedora) that uses ext4 is perfectly fluent. Any install based on ext3 is atrocious.
The most obvious explanation, though possibly wrong, is that under ext3 the kernel jobs schedulers do not take into account the time/bandwidth used by each job regarding disk accesses. A worst case situation is a simple cp of a huge file. The cp command uses almost no CPU resources but maximum hard disk bandwidth. Aside of this, say Firefox is starting. It uses quite a lot of hard disk bandwidth but also a fair amount of CPU. The scheduler notices that the poor devil of a cp uses almost no resources, because only the CPU consumption is taken into account. So, the cp command is unleashed to maximum liberty while the apparently evil Firefox is constrained. Having all CPU time it wants, cp will seize almost all the hard disk bandwidth. Firefox may then need up to several minutes to start. Even simply displaying a menu, if it implies reading a little file, may take several seconds. (What's more, if the huge file copied by cp is bigger than the available RAM, it will constantly erase all other cached files, even though caching the huge file is bluntly pointless.) A system installed in an ext4 formatted partition is wonderfully fluent, to the smallest details. It's like every job had all the resources for itself and all the system was compelled to please you instantly. (Note that an ext4 partition can have no boot record, so you have to use a separate little /boot partition formated in ext3, or any alternate responsible solution.) I tried using other graphical interfaces, like AfterStep and fvwm. The problem got even worse... It was really frightening under Afterstep, making the system unusable. My guess is that Metacity is quite a neat window manager after all, though some versions may be even nicer than others regarding this problem. -- [jaunty] cpu scheduling is not optimized for multitask https://bugs.launchpad.net/bugs/363663 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
