Re: MM deadlock [was: Re: arca-vm-8...]

Stephen C. Tweedie
1999-01-26T13:11:33Z

Hi,

On Mon, 25 Jan 1999 22:59:00 +0100 (MET), Gerard Roudier
<groudier@club-internet.fr> said:

> If you tell me that some system XXX is able to quickly free Mega-Bytes of
> physical contiguous memory at any time when it is asked for such a
> brain-deaded allocation, then for sure, I will never use system XXX,
> because this magic behaviour seems not to be possible without some
> paranoid VM policy that may affect badly performances for normal stuff.

It is really not hard to reserve a certain amount of memory (up to some
fraction, say 25% or 50% of physical memory) for use only by pagable
allocations. Most desktop boxes will _not_ require more than 50% of
memory for locked kernel pages. Recovering any given range of
contiguous pages from that pagable region may be expensive but will
_always_ be possible, and given that it will usually be a one-off
expense during driver setup, there is no reason why we cannot support
it.

--Stephen
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