On Wed, 9 Jun 1999, Eugene Kuznetsov wrote:
> On Wednesday, June 09, 1999 1:11 PM, Joe [SMTP:[EMAIL PROTECTED]] wrote:
> > Netscape uses threads which in turn use "buzz" locks, (or short
> > spin locks) for mem locking. (OK)
>
> Netscape uses user-mode threads, if I remember correclty, although perhaps
> they're switching to real threads. That would mean one process, and some
> really unpleasant (and hang-prone) code switching contexts. (SIGALRM,
> etc.).
>
> The whole question of whether "native" (i.e. _not_ usermode) threads should
> be supported directly by the kernel or via processes is rather contentious.
> It bites both ways -- if one is moving from Linux to NT, the first thought
> is: "NT stinks, the process creation overhead is terrible." The answer is:
> "Well, you should be using threads (or fibers)." Coming from NT to Linux,
> the first two thoughts are: "Linux stinks, it has only user-mode threads"
> or "Linux stinks, if you want to use preemptive threads, you end up
> creating one process per thread, plus a manager process, and that must be
> slow!". The answer is: "Yes, it does have native mode threads, and the
> process overhead for Linux is less than that for NT."
I don't follow. Linux _only_ has kernel-mode threads. Each thread is a
unique process with its own PID and context. Linux is just real slick
on doing the fork() by using the copy-on-write page-sharing trick...
But kernel-mode they are, and that is _all_ that you can do unless you
write your own thread library. IE the pthreads library uses kernel-level
processes for each thread...
>
> So it's really a deep architectural debate, with pressure on Linux to get
> special handling for processes that are really threads (e.g. keep all
> "process threads" on the same processor, etc.) [re: linux-kernel a few
> weeks ago] and with pressure on NT to get "lighter processes" (threads,
> fibers, etc.).
linux _never_ keeps all threads on the same cpu. Unless you only have one
cpu...
>
> IMHO, in the future there will be convergence, with NT and Linux coming
> towards each other on some of these issues.
I hope NT comes toward Linux... :) Otherwise Linux will start
to suck. :)
>
> Eugene Kuznetsov
>
>
>
>
>
>
-
Linux SMP list: FIRST see FAQ at http://www.irisa.fr/prive/mentre/smp-faq/
To Unsubscribe: send "unsubscribe linux-smp" to [EMAIL PROTECTED]
