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Graphics Hardware IT

Visualizing System Latency 68

ChelleChelle writes "Latency has a direct impact on performance — thus, in order to identify performance issues it is absolutely essential to understand latency. With the introduction of DTrace it is now possible to measure latency at arbitrary points; the problem, however, is how to visually present this data in an effective manner. Toward this end, heat maps can be a powerful tool. When I/O latency is presented as a visual heat map, some intriguing and beautiful patterns can emerge. These patterns provide insight into how a system is actually performing and what kinds of latency end-user applications experience."
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Visualizing System Latency

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  • by bzdang ( 819783 ) on Wednesday June 02, 2010 @05:37PM (#32437684)
    Back in the day, working at an instrumentation company as a mechanical guy, I stopped to watch the senior electronic design engineer who was doing something that looked interesting. He had an old persistence-type storage oscilloscope hooked up to the rack-mount computer for a new instrument system and was watching the scope display, which was producing some fascinating patterns. Knowing f'all about this stuff but intrigued, I asked him to explain what was happening. He explained (and I'll butcher the explanation with layman's terms) that he was using d/a converters on the high and low bytes of the program address? to drive the x and y axes of the scope, and watching to see where, in the software, that the processor was spending much of it's time. He pointed to a hot spot on the scope display and said that this was where he would concentrate on optimizing his code. Fwiw, I thought that was pretty cool.

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