5+ years ago it was pretty common for folks to modify the Linux kernel or 
run cut down OS implementations when pushing the edge of HFT. These days 
the really fast stuff is all in FPGAs in the switches. However there is 
still work done on isolating threads to their own exclusive cores. This is 
often done by exchanges or those who want good predictable performance but 
not necessarily be the best.

A simple way I have to look at it. You are either predator or prey. If 
predator then you are mostly likely on FPGAs and doing some pretty advanced 
stuff. If prey then you don't want to be at the back of the herd where you 
get picked off. For the avoidance of doubt if you are not sure if you are 
prey or predator then you are prey. ;-)

On Sunday, 8 April 2018 13:51:52 UTC+1, John Hening wrote:
>
> Hello,
>
> I've read about thread affinity and I see that it is popular in 
> high-performance-libraries (for example 
> https://github.com/OpenHFT/Java-Thread-Affinity). Ok, jugglery a thread 
> between cores has impact (generally) on performance so it is reasonable to 
> bind a specific thread to a specific core. 
>
> *Intro*:
> It is obvious that the best idea to make it possible that any process will 
> be an owner of core [let's call it X] (in multi-core CPU). I mean that main 
> thread in a process will be one and only thread executed on core X. So, 
> there is no problem with context-switching and cache flushing [with expect 
> system calls]. 
> I know that it requires a special implementation of scheduler in kernel, 
> so it requires a modification of [Linux] kernel. I know that it is not so 
> easy and so on.
>
> *Question*:
> But, we know that we have systems that need a high performance. So, it 
> could be a solution with context-switching once and at all. So, why there 
> is no a such solution? My suspicions are:
>
> * it is pointless, the bottleneck is elsewhere [However, it is meaningful 
> to get thread-affinity]
> * it is too hard and there is too risky to make it not correctly
> * there is no need
> * forking own linux kernel doesn't sound like a good idea.
>
>
>

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