yodaiken@fsmlabs.com wrote on 23.08.00 in <20000823172504.A733@hq.fsmlabs.com>:
> On Wed, Aug 23, 2000 at 10:54:57PM +0200, Andi Kleen wrote:
> > The users do not distingush between kernel thread and thread. They just
> > want a thread and assume it is lightweight. Linux effectively gives them
> > only heavy threads currently, which they usually do not need.
>
> Linux processes are more lightweight than "threads" on many operating
> systems. As Rob Pike pointed out many years ago: a perceived need for
> "threads" means that processes are poorly designed.
*Only* if the perceived need comes from performance issues.
Threads are a rather nice programming abstraction *if used right*, and
processes (i.e. threads without shared memory) certainly aren't a
reasonable replacement, just as you wouldn't want to replace subroutines
with processes.
In *this* role, performance is a rather secondary issue (unless it's
abysmally bad).
Coroutines can do a lot of this, but as soon as you have hard-to-predict
scheduling, or want to block on system calls, you want real threads, not
coroutines.
MfG Kai
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