Add the rest of university notes

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John Gatward committed 2026-10-04 14:02:35 +01:00
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@@ -22,7 +22,7 @@ The operating system provides **memory abstraction** for the user. Otherwise mem
#### Partitioning
![img](/lectures/osc/assets/A.png)
![img](assets/A.png)
##### Contiguous memory management
@@ -52,7 +52,7 @@ Where memory is allocated in multiple blocks, or segments, which may not be plac
>
> * Overlays enable the **programmer** to use **more memory than available**.
![img](/lectures/osc/assets/B.png)
![img](assets/B.png)
##### Short comings of mono-programming
@@ -77,7 +77,7 @@ Why Multi-Programming is better theoretically
> * The probability that **all** *n* **processes are waitying for I/O is *p*^n^
> * Therefore CPU utilisation is given by $1 - p^{n}$
![cpu_util_form](/lectures/osc/assets/C.png)
![cpu_util_form](assets/C.png)
With an **I/O wait time of 20%** almost **100% CPU utilisation** can be achieved with four processes ($1-0.2^{4}$)
@@ -85,7 +85,7 @@ With an **I/O wait time of 90%**, 10 processes can achieve about **65% CPU utili
CPU utilisation **goes up** with the **number of processes** and **down** for **increasing levels of I/O**.
![cpu_util_graph](/lectures/osc/assets/D.png)
![cpu_util_graph](assets/d.png)
**Assume that**:
@@ -124,7 +124,7 @@ CPU utilisation **goes up** with the **number of processes** and **down** for **
* Reduces **internal fragmentation**
* The **allocation** of processes to partitions must be **carefully considered**.
![process_alloc](/lectures/osc/assets/E.png)
![process_alloc](assets/E.png)
**One private queue per partition**: