Starting and joining a lot of threads slower on AMD systems compared to Intel systems

[Aleksey Shipilev]

In addition to excellent Thomas Stuefes' reply:

On 5/15/21 10:15 PM, Waishon wrote:
> In a study project we should create 100.000 threads to get a feeling for the time it takes to
> create a lot of threads and why it's more efficient to use tasks instead.
I think what you found is in the spirit of the assignment: not only you discovered the overheads are 
high, but also that they are different across systems, OSes, etc.

> What might be the reason why starting and joining threads is so much slower on AMD systems
> compared to Intel systems?
> 
> (Disclaimer: This question was also posted on Stackoverflow, which referred to this mailing list:
> https://stackoverflow.com/questions/67550679/creating-threads-is-slower-on-amd-systems-compared-to-intel-systems)
Well, could be a number of things. Most likely, since we are dealing with OS syscalls on thread 
creation, we are probably doing mostly memory and task management for new threads. But to know more, 
you need to follow the advice of the very first SO comment: "You should probably use a profiler and 
it will better tell you where the time is being spent." [1]

For example, with async-profiler [2] would profile both Java, JVM and kernel code:
  $ java 
-agentpath:$asyncProfilerPath/libasyncProfiler.so=start,event=cpu,frequency=10000,file=profile.html 
ThreadCreator

-- 
Thanks,
-Aleksey

[1] 
https://stackoverflow.com/questions/67550679/creating-threads-is-slower-on-amd-systems-compared-to-intel-systems#comment119397887_67550679
[2] https://github.com/jvm-profiling-tools/async-profiler