Is swap really needed when RAM's aplenty

[Michael Hennebry]

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."