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Re: Next steps in improving single-threaded performance


Hi Kristian

On 04/22/2014 04:11 PM, Kristian Nielsen wrote:
As a side effect, if we improve the code performance of a single thread, we
effectively increase the concurrency in the critical spots - threads spend
less time executing the real code, hence more time in concurrency
bottlenecks. The end result is that _any_ change that improves single-threaded
performance causes throughput to decrease at concurrency levels where the code
falls over.

I have a more "education" focused question, rather than commenting on the issue or the results/arguments.

What do you mean with the phrase [code|server] "falls over"?

Also a quote from https://lists.launchpad.net/maria-developers/msg07210.html :

Basically, the server "falls over" and starts trashing instead of doing real work, due to some kind of inter-processor communication overhead.

I understand the concept of a program spending increased time in
  a) switching or scheduling switches
  b) communication between threads
during increased concurrency levels. I am simply wondering if you mean anything more specific.

Forgive my ignorance, and the thread hijacking :)


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