L4 pager

Marcus Voelp voelp at os.inf.tu-dresden.de
Sun Dec 19 11:10:21 CET 2010


On 12/17/2010 04:59 PM, Ashford Nichols wrote:
> I am new to L4 microkernels and I am reading the reference manual on 
> version 2 of the interface. From what I've read so far the manual 
> suggests that there's more than one pager, but if this is so what 
> is the purpose of more than one pager?
A pager of a thread A is just the thread (portal, gate) to which the
kernel delivers A's page-fault messages. Every thread has precisely one
such pager but of course you can construct arbitrary complex scenarios
on top of this mechanism. One typical scenario is what is called a
region manager. The region manager thread acts as a pager for the
threads in an address space and forwards their page-fault requests to
the memory managers that are responsible for the individual regions of
the address space (e.g., code, memory mapped files or anonymous memory
such as stack or heap). Unfortunately, we sometimes call the latter
"pager" because they are meant to actually resolve the page-faults.

Hope this helps


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