Re: Active Memory Defragmentation: Our implementation & problems

[IWAMOTO Toshihiro]

At 03 Feb 2004 23:10:52 -0800,
Dave Hansen wrote:
> remap_onepage() is quite a function.  300 lines.  It sure does cover a
> lot of ground. :)
> 
> Defragmentation is a bit easier than removal because it isn't as
> mandatory.  Instead of having to worry about waiting on things like
> writeback, the defrag code can just bail.  

Waiting for !pagewriteback and writing back page at the beginning of
remap_onepage() are a sort of "easy part".
We need to wait for exclusive access of a page before copying anyway,
and interesting things such as vmtruncate can happen while waiting for
it.

I don't think the code can be much shorter without assuming a single
processor !CONFIG_PREEMPT system.

--
IWAMOTO Toshihiro
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