What is a Pager

[Ashford]

hey all,
I've come across the concept of paging many times in the past two days and the word pager pops up every now and then. However, I don't understand what a pager is since references to it are very vague. Does it control paging operations, and also how many are there an an OS.

thanks in advance.

 

[Sceadwian]

In reference to what? Your question is vague.

 

[Sceadwian]

In reference to what? Your question is vague.

and also how many are there an an OS.

I'm not even sure what kind of question that might be.

 

[blueroomelectronics]

A pager is a device used mostly by drug dealers in the last century.
**broken link removed**
Apparently the almighty has one too.

 

[Ashford]

Ok, since i asked the question I figured out that apparently a pager is responsible for carrying out paging operations in an operating system. However, I'm still not sure how many are present in one operating system. If my explanation is still vague here's an article on Wikipedia

 

[BrownOut]

A pager is a device used mostly by drug dealers in the last century.

Heh, heh, heh... Very true

 

[RODALCO]

We use them in the NZ Fire Service to page volunteers (from home) and paid staff (on station) to attend to fire calls.

 

[KeepItSimpleStupid]

I agree. The explanation seems vague.

I'll put it this way. Paging needs both hardware and software. let's call the hardware the "Memory management unit (MMU)" and call the "pager" the device driver for the MMU. Hence one unless we introduce the concept of virtual machines.

 

[Sceadwian]

The question is vague, there should only be one pager in the system and it should be part of the kernel. Since you're not even referencing an operating system there's really nothing to talk about.

 

[Ashford]

I was talking in general as in operating systems in general, kind of like how we know "generally" there is only one scheduler, or one MMU in a CPU. But never mind I figured it out. There's generally one pager per OS (except in the case of L4 microkernels).

 

[3v0]

Why does L4 need more then one pager ?

 

[Ashford]

The multi-pager system allows each address space to have its own pager, which is really a region manager. Also, the portal to which a thread's page-fault messages are delivered to, in L4 micro-kernels, are refered to as pagers.

 

[PatM]

Paging - Wikipedia, the free encyclopedia

 

[gabeNC]

Very much like a hypervisor. To throw even more variables into this thread, read up on memory overloading/expansion using virtualization software (AIX, vmware etc). Here's some marketing fluff but gives a decent overview.

https://www.electro-tech-online.com/custompdfs/2010/12/POW03037USENPDF.pdf

 

[3v0]

In CS there are often a few different ways to do same job.

If I put on my OO hat we can create a pager class. Each pager instance manages one address space. Similar results could be obtained from a function that could act on multiple data sets.

How many pagers are there? It may depend on which hat you are wearing and what glasses you are looking through. If you squint.... you can still see the one pager class with it methods under the object.

 

[RODALCO]

Attached is a photo I currently use for the fire brigade.

 

[ben7]

Ah yes rodalco, I knew you were interested in the fire brigade too from your youtube channel.
Do you listen for working fires, and when there is one do you go to see it?
In the US people (like me) who do that are called Squirrels

My dad is a firefighter and he has a pager. Whenever a call comes in for his fire station, his pager goes off beep,beep,beep,beep...

-Ben