user/kernel level thread and thread's models mapping

[maria belliti]

Hi

I wish to be personally CC'ed the answers/comments posted to the list in 
response to this post

Theoritically, user level thread ensures thread management , such as
scheduling and context switch, to be performed without a system call
i.e Kernel intervention whereas with kernel level threads, kernel is
aware about the threads and the context switch is done by the kernel
which requires then a system call and mode switch. Meanwhile there are
three models to map user threads to kernel threads: one to one, many
to many, many to one.

My question is how can we have a conjunction of user level thread and
many to many model (or one to one model)? One to one model maps each
user thread to kernel thread which are normally used to perform
context switch at the kernel level (mode). However user level thread
dictates that context switch should be done without kernel
intervention!!

I read that Java switched from green to native mode, which involves
one to one model mapping and yet it is said that context switch is
done at the user level with no intervention from the kernel... that's
my confusion

thanks

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