BFS vs. mainline scheduler benchmarks and measurements

When I was going to do something that might get away from me (fork lots of
processes doing something), I would try to remember to 'nice --20 sh' in
another window. Because I would often have the boundary condition wrong
and would generate 20 000 to 40 000 processes running BTTW. That one
nice'd shell would save me almost every time. I've done this on my AT&T
UNIXPC, and systems running SysV/68, SysV/88, Irix, SunOS[345], Linux,
BeOS, BSD, and others.

There have been times in the past when nice'ing the X server improved
performance on my single-proc PIII-866; for 5-10 years now, only two or
more CPUs let X run smoothly.

There have been times in the past when nothing would smooth out the
choppiness of the EXT2/3 driver under heavy R/W load, whether I had two
PII-266's or a PIII-866. I solved that problem by switching to ReiserFS.

In recent years and on two completely different systems, I've noticed a
tendency for the kernel to do weird things with the PS/2 drivers (system
slows down, gets choppy, and even silently resets). This last time, I
pulled the plugs for the PS/2 ports and the system returned to normal.
(The chipset fan was overworking itself, so I had *some* clue where to
look.)

There can be many reasons why a system is 'choppy', and it's not always
the scheduler. Sometimes it's the interrupt handler dealing with some
device that's gone haywire. Sometimes it's the block layer not doing disk
I/O very nicely or a server process being very inefficient. Sometimes it's
an application that's gone braindead. And if a scheduler can be developed
that smooths out the choppiness in single- and dual-core systems, great!
Go for it! An older single-CPU system may never be fast, but it ought to
run smoothly under normal user operations.

The scheduler has gotten better over the past 15 years. And it will
continue to improve. But apps have to improve as well and not always
assume the 'system' will take care of everything.

As Ingo says, 8-core systems aren't mainline. But they will be. Perhaps
Con is looking to improve today's mainline systems, not tomorrow's. Is
this apples v. oranges? Or is it ain't? Mayhap never the twin shall meet.
But all parties involved should strive to keep the discourse civil and
positive.