Re: 2.1.125 Show stopper list: Draft

Alan Cox (alan@lxorguk.ukuu.org.uk)
Tue, 13 Oct 1998 19:44:09 +0100 (BST)


> 2. Free page tables when they're emptied, by keeping up to date
> per-page-directory counts of used entries.
>
> Doesn't do anything about the overheads, but hopefully keeps them
> bounded as a proportion of the actual page table memory used.
>

NetBSD handles this very elegantly. Because the overhead of page
table recovery is pretty foul (especially non intel), when they need
to reclaim memory urgently they simply blow the CPU page tables away
and give the task a new empty page table set to page everything back
into.

Since there are caches these faults don't go to disk but just to the cache
and rapidly recover the page tables for the current working set.

Alan

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