* David Petrou <[EMAIL PROTECTED]> [001127 14:10] wrote:
> hi. i've searched the handbook, tutorial, FAQ, and parts of the
> mailing list archives but haven't found direct answers to the
> following questions. i hope you don't mind answering them for me; it
> will save me a lot of time looking through the code, and / or writing
> test cases:
>
> let's say i'm running 4.x-stable.
>
> 1. if i use the pthreads interface, is each thread a process that
> happens to share the same addr space (like linux), or are all the
> threads part of the same single process (same PID)?
The latter.
> 2. is the threading preemptive? or do i have to explicitly yield?
Former.
> 3. if preemptive, does that occur at user-level, or by the kernel?
> (and how costly is it?)
It's a mix, and very cheap.
> 4. if one thread makes a system call that could block for some time,
> will another thread be automatically chosen? or will the whole
> collection of threads sleep until the call returns?
Latter. However our threads model wraps most syscalls so that you
shouldn't block, you can still block on disk IO, however I have
a proposal that I (or someone else) might implement in the near
future to fix this.
> 5. if i signal a particular thread, is the signal delivered to one
> thread or to all the threads in the process?
We should follow the pthreads standard for this, check the standard.
> 6. if a thread or process (terminology sucks) enters the kernel, can
> the scheduler preempt it and select another thread / process to
> run? (q.v., what many people call having kernel threads.) or will
> that process / thread dominate the system until it voluntarily
> relinquishes the processor?
Latter.
> 7. are there other threads interfaces besides pthreads that i should
> be aware of? what are the differences? e.g., assuming freebsd
> supports a clone()-like interface, do some threads packages use it
> while others do as much as they can without kernel support?
the native threads are what conforms to the answers I have you above,
there's a port called "linux-threads" in the ports collection to
do what Linux does (clone()-like pid-per-thread)
> i'm probably forgetting some questions, but these are the bulk. i'm
> just wondering what the current thread model is as i contemplate
> moving my development to FreeBSD.
Well you have a choice between our threads model and the Linux model
on FreeBSD. I've been contemplating some changes that would
speed up our threads with regards to disk/IO, but that's a way
off.
--
-Alfred Perlstein - [[EMAIL PROTECTED]|[EMAIL PROTECTED]]
"I have the heart of a child; I keep it in a jar on my desk."
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