Re: memory hotremove prototype, take 3

From: Hirokazu Takahashi
Date: Tue Dec 02 2003 - 01:31:05 EST


> > > During hotunplug, you copy pages to new locaion. Would it simplify
> > > code if you forced them to be swapped out, instead? [Yep, it would be
> > > slower...]
> >
> > There are some pages that will have to be copied (e.g. pages that
> > the user "mlock()d" should still be locked in their new location,
> > same for hugetlbfs pages).

And some pages which aren't associated with backing store like sysfs or
ramdisk have to be, too.

> Using kswapd is easy, but doesn't always work well. The patch
> contains the code to ignore page accessed bits when kswapd is run on
> disabled zones, but that's not enough for swapping out frequently used
> pages.
> In my patch, page copying, or "remapping", solves this problem by
> blocking accesses to the page under operation.

Thank you,
Hirokazu Takahashi.
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