Some specific questions about 5.x

[Terry Lambert]

Alex wrote:
> I was so much enthusiastic about kernel threads implemented in 5.x but
> some ugly rumors spoiled my dreams :0)
> So I want to get if these rumors are myths or not.

5.x does not implement traditional "kernel threads" like you appear
to be thinking about them.  Instead, it implements a variation of
scheduler activations.  Traditional "kernel threads" have a lot of
unnecessary overhead problems, including CPU affinity and thread
group negaffinity, necessary for increased single application
concurrency.

See the KSE documentation for more information.


> 1.    Is it true that kernel threads are more "heavy" than userspace
> ones (pthread) and hence application with hundreds of threads will work
> evidently slower than that using pthreads due to more switching penalties?

Yes and No.

See the KSE documentation for more information.

> 2.    Is it true that even 5.x has no implementation for inter-process
> semaphores that are blocking calling thread only not the whole process
> as usually in FreeBSD?

No, for values of x > 0.

See the KSE documentation for more information.

-- Terry