Re: [PATCH] swapin readahead and fixes

Billy Harvey (Billy.Harvey@thrillseeker.net)
Mon, 07 Dec 1998 21:51:51 -0500

Rik van Riel wrote:
>
> On Mon, 7 Dec 1998, Billy Harvey wrote:
>
> > Has anyone ever looked at the following concept? In addition to a
> > swap-in read-ahead, have a swap-out write-ahead. The idea is to use
> > all the avaialble swap space as a mirror of memory.
>
> We do something a bit like this in 2.1.130+. Writing out all
> pages to swap will use far too much I/O bandwidth though, so
> we will never do that...
>
Rik,

That's my point though about not taking I/O time away from other tasks.
Only mirror pages to swap if there's nothing else blocked for I/O - put
any free time to work, and mirror pages if swap memory allows in
anticipation that it may be swapped out later. I suppose a
least-recently-used approach on the pages would have the highest
payback. I realize the CPU may be used a little more, but other than
rc5des it's idle a good bit of the time anyway - perhaps this could be
one step above an idle task.

Billy

-- 
Billy.Harvey@thrillseeker.net


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