# Lab3a: Demand Paging

{% hint style="warning" %} <mark style="color:red;">**Code Due: Thursday 05/28 11:59 pm**</mark>

<mark style="color:red;">**Design Doc Due: Sunday 05/31 11:59 pm**</mark>
{% endhint %}

**By now you should have some familiarity with the inner workings of Pintos.**

* Your OS can properly handle multiple threads of execution with proper synchronization, and can load multiple user programs at once.
* However, the number and size of programs that can run is limited by the machine's main memory size. In this assignment, you will remove that limitation.

<mark style="color:red;">**You will build this assignment on top of the last one.**</mark>

**Test programs from project 2 should also work with project 3.** You should take care to fix any bugs in your project 2 submission before you start work on project 3, because those bugs will most likely cause the same problems in project 3.

**You will continue to handle Pintos disks and file systems** **the same way you did in the previous assignment** (see section [Using the File System](/pintos/project-description/lab2-user-programs/background.md#using-the-file-system)).

**Here are the sections in this chapter:**

{% content-ref url="/pages/7CDg5BuFoMT890xs77PL" %}
[Background](/pintos/project-description/lab3a-demand-paging/background.md)
{% endcontent-ref %}

{% content-ref url="/pages/G91x7wqZaI3D3TFo4y92" %}
[Suggestions](/pintos/project-description/lab3a-demand-paging/suggestions.md)
{% endcontent-ref %}

{% content-ref url="/pages/8sOVTpAGNhG16MBPOU9S" %}
[Your Tasks](/pintos/project-description/lab3a-demand-paging/your-tasks.md)
{% endcontent-ref %}

{% content-ref url="/pages/hlxgdYdNHAr1SP9B4ejA" %}
[FAQ](/pintos/project-description/lab3a-demand-paging/faq.md)
{% endcontent-ref %}

{% content-ref url="/pages/Fc3d23fZkXRD9PUGWxB1" %}
[Submission](/pintos/project-description/lab3a-demand-paging/submission.md)
{% endcontent-ref %}


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://pkuflyingpig.gitbook.io/pintos/project-description/lab3a-demand-paging.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.