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SubjectRe: [PATCH] self tuning scheduler

I took your patch out for a test-drive, and it appears to have starvation
problems with irman's process load (dang thing seems to be HELL on schedulers).

Irman starts a load (defaults to 9 tasks passing data in a pipe ring), and
forks a child which pingpongs one character back and forth to the parent
for 1000000 iterations, measuring response time for each iteration and
computing statistics. With an iteration % 1000 printf() in the evaluation
routine, I see it start off nice and fast, then begins to get starved for
up to 30 seconds. It jerks around for a bit, then slows down to a ~stable
1 sec/iteration after approximately 300000 iterations. The whole test
takes ~2minutes with 2.5.64-virgin. (I'm not patient enough to wait for
the rest of the .5million iterations left on this burn before reporting:)

It also shows a serious throughput loss with make -j30 bzImage on this box
(I think you expect that though from what I read). With stock, it takes
~8m30s... this scheduler adds a full minute.

The window wave test with a make -j5 bzImage running (fits easily in ram)
is pretty ragged.

Ending on a more positive note, vmstat output from the parallel build looks
quite nice.


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