
Broken Performance Tools [pdf] - yunong
http://www.brendangregg.com/Slides/QCon2015_Broken_Performance_Tools.pdf
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nkurz
This is a nice summary of Linux performance monitoring tools.

What does he mean with his repeated question "Why isn't it 10x?"

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brendangregg
If you benchmark a product and it does 13,000 req/sec (or whatever), then
answer the question of why it isn't doing 130,000 req/sec. It's a way of
encouraging you to debug it further.

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nkurz
Got it, thanks! For me the better question is often simply "Why is it X?"
Knowing why the speed is X is often of much greater utility than simply
knowing that X is the speed. I like to focus on determining the current single
limiting factor before considering the harder question of what would be
necessary to achieve 10x.

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brendangregg
If you know the limiter, you know why it isn't 10x. It's CPU bound. It's disk
bound and we're on a single disk. etc.

How do we actually make it 10x? is a follow on question, but as you say, not
one that may be easy to answer!

