The 2.5 development kernel introduced multiple changes intent on improving the interactive performance of Linux. Unfortunately, the term "interactive performance" is rather vague and lacks proper metrics with which to measure. Instead, we can focus on five key elements:

• fairness
• scheduling latency
• interrupt latency
• process scheduler decisions
• I/O scheduler decisions

In short, these attributes help constitute the feel of Linux on the desktop and the performance of Linux in real-time applications. As Linux rapidly gains market share both on the desktop and in embedded solutions, quick system response is growing in importance. This paper will discuss these attributes and their effect on interactive performance.

Then, this paper will look at the responses to these issues introduced in the 2.5 development kernel:

• O(1) scheduler
• Anticipatory/Deadline I/O Scheduler
• Preemptive Kernel
• Improved Core Kernel Algorithms

Along the way, we will look at the current interactive performance of 2.5.

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