Is swap really needed when RAM's aplenty
hennebry at web.cs.ndsu.nodak.edu
Thu Aug 19 21:20:32 UTC 2010
On Thu, 19 Aug 2010, Patrick O'Callaghan wrote:
> On Thu, 2010-08-19 at 09:22 -0500, Michael Hennebry wrote:
>> On Thu, 19 Aug 2010, Gregory Hosler wrote:
>>> If the memory gets fragged and the kernel wants to defrag, e.g. for a memory
>>> request from an application, in order to defrag any "dirty" data portions (those
>>> pages that have been written to), the kernel *requires* there to be swap.
>>> Otherwise there is no place to write the dirty pages out, in order to read them
>>> in elsewhere.
>> I didn't realize that memory could get fragged.
>> I'd thought that one reason for virtual memory
>> was allowing pages to be renumbered at will,
>> the kernel's will, of course.
> I thought so too, but see: http://lwn.net/Articles/211505/
Posted November 28, 2006 by corbet:
> If a large ("high order") block of memory is not available when needed,
> something will fail and yet another user will start to consider switching to BSD.
BSD does it differently?
Michael hennebry at web.cs.ndsu.NoDak.edu
"Pessimist: The glass is half empty.
Optimist: The glass is half full.
Engineer: The glass is twice as big as it needs to be."
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