The Really Fair Scheduler

derrida writes "During the many threads discussing Ingo Molnar's recently merged Completely Fair Scheduler, Roman Zippel has repeatedly questioned the complexity of the new process scheduler. In a recent posting to the Linux Kernel mailing list he offered a simpler scheduler named the 'Really Fair Scheduler' saying, 'As I already tried to explain previously CFS has a considerable algorithmic and computational complexity. This patch should now make it clearer, why I could so easily skip over Ingo's long explanation of all the tricks CFS uses to keep the computational overhead low — I simply don't need them.'"

Comments

But where is the Linux IO Scheduler?

[Anonymous Coward]

Screw the CPU scheduler at this point. The kernel folks are missing the obvious and utter brokenness of the IO scheduling. These bugs have been outstanding about a year now!! And it's not just AMD64 anymore either. Quoth the kernel bug report:

"Now, as far as this bug being AMD64 only. We develop a portable data analysis
tool and we run it on Intel Core Mobile systems (Sony UX series, Panasonic
Toughbook series) and see this bug or one almost exactly like it on those
platforms as well.
"

http://bugzilla.kernel.org/show_bug.cgi?id=7372
http://bugzilla.kernel.org/show_bug.cgi?id=8636
http://www.nabble.com/IO-activity-brings-my-deskto p-to-its-knees-(2.6.22.1-ck1)-t4192136.html
http://forums.gentoo.org/viewtopic-t-482731-start- 500.html

At first, deadline IO was touted as an answer, but that doesn't completely fix things.
Some say Native Command Queueing is broken. One person claims deadline + NCQ disabled helps.
Some say the kernel's vfs_cache_pressure settings help, while others refute it (compare kernel bug report versus page 21 of the gentoo forum thread). But no one understands what's really broken in the kernel.

Can we please get Ingo working on IO scheduling? PLEASE?