Re: [PATCH] free swap space of (re)activated pages

[Rik van Riel <riel@redhat.com>]

Andrew Morton wrote:
> On Fri, 02 Mar 2007 15:31:19 -0500
> Rik van Riel <riel@redhat.com> wrote:
> 
>> the attached patch frees the swap space of already resident pages
>> when swap space starts getting tight, instead of only freeing up
>> the swap space taken up by newly swapped in pages.
>>
>> This should result in the swap space of pages that remain resident
>> in memory being freed, allowing kswapd more chances to actually swap
>> a page out (instead of rotating it back onto the active list).
> 
> Fair enough.   How do we work out if this helps things?

I suspect it should mostly help on desktop systems that slowly
fill up (and run out of) swap.  I'm not sure how to create that
synthetically.

I have seen that swap is kept free much easier in a qsbench
test, but that's probably not a very good test since it swaps
things in and out all the time...

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