VM idle page zeroing
dillon at apollo.backplane.com
Sun May 16 17:24:14 PDT 2010
:Any particular reason for moving the thread to the last cpu?
No, It is just an experiment. There is no need to put it on cpu 0
on a SMP system since numerous dedicated threads already run on cpu 0.
It can't hurt, anyhow.
:Something that occured to me - right now, we have a thread that wakes up
:every 1/10th of a second, checks if there are pages to zero. At long
:stretches of idle time, we just end up waking and sleeping a whole lot.
:Instead, perhaps, when vm_page_zero_check() sees that we hit ZIDLE_HIGH we
:should perhaps sleep for a lot longer and drop down to the usual rate when
:we hit ZIDLE_LOW?
Yes and no. Yes it is probably worth doing as sleep states become
more advanced. But on the flip side the actual cpu use is miniscule,
less than 0.01%. Essentially 10uS once every 1/10 second and with
no locking requirements in the no-work case.
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