[FreeBSD] kezdo bsds kerdes

[Kulcsár Ferenc]

Sziasztok,

>
> > > Az OpenBSD-nek (3.0-as verziotol) van tovabba egy sajat fejlesztesu
> > > csomagszuroje (PF) is.
> > Ez kissé félreérthető.  A Free-nek is van saját fejlesztésű, az ipfw.
> Igy van. En csak az OpenBSD-s reszhez szoltam hozza, de igy kerek a
> tortenet.
>

eloveve a gombolyu reszelomet meg tovabb kerekitek. A NetBSD csapat is
gozerovel dolgozik az SMP-n, mar mukodik Alpha es VAX eseteben, az i386
kozel all a befejezeshez. Egy kis izelito a remelem nagyon kozeli jovorol:

> - FreeBSD has SMP.
> We don't need this right away but we will eventually.  We could really
> use more upfront discussion on where we are on this.  To most people
> it looks like we have no SMP support and we have no idea when we will.

AFAIK the SMP branch i386mp is getting close to be integrated
to mainstream. It's recognized as 'must have soon'. Lingering
problems are being hashed out (/cookie's to people involved).

"> - FreeBSD has working threads.
> This is the biggest issue.  It seems that we can't get threads right for
> some reason.  There are things we want to do that really depend on this.
> None of the thread packages in the pkgsrc tree seem to work 100%.

The port-specific parts of Nathan's Scheduler Activations based
pthreads are currently being finished, and the branch is expected
to be merged to mainstream 'soon' (hopefully). Note SA-based threads are far
superiour than the current FreeBSD thread code, and should put us
to same level of performance/support as e.g. threading in Solaris
(once stabilized).

I've just recently learned that current FreeBSD-stable threads are
pure userland, so only one system call can be executed by any thread
any time. If this is true, this means that e.g. if a read() issued by one
of the threads blocks, all other threads within the process block too.
The Nathan's SA pthreads should not have this limitation, multiple
threads ("lwps") can be making syscall and be blocked in kernel,
while other lwps doing userland-only stuff happily continue running.
This should offer significant concurrency and performance advantage
in common cases, while maintaining low context switch advantage
of userland threads (mmmmm, SAs :).

IIRC there is KSE (Kernel Schedul Entity) project in FreeBSD which
is aimed to write SA-like threads. However, that is FreeBSD-current
thing, and not going to be shipped before FreeBSD 5.0. AFAICS,
FreeBSD 5.0 is scheduled to early 2003.

Jaromir"


PS:
Szemely szerint nem tudnek valaszt adni arra a kerdesre, hogy melyik BSD-t
hasznald. En a NetBSD-t uzom, mert szeretem ;-)).