Re: SCO: "thread creation is about a thousand times faster than onnative

From: Andi Kleen (ak@suse.de)
Date: Wed Aug 23 2000 - 15:54:57 EST


On Wed, Aug 23, 2000 at 01:46:49PM -0700, Linus Torvalds wrote:
>
>
> On Wed, 23 Aug 2000, Andi Kleen wrote:
>
> > On Wed, Aug 23, 2000 at 09:17:10PM +0100, Alan Cox wrote:
> > > The kernel has fast lightweight threading. How you map user space threads and
> > > co-routines onto this is really between the app and libs. In fact I'd argue
> > > strongly that an app _must_ be able to provide its own strategy routine or
> > > some kind of hints to the lib
> >
> > I would not call 8K/16K overhead "lightweight" treading.
>
> Oh, and pray tell how much you expect a kernel thread to take?

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.

(like the "posix programmer
knows the availability of everything, but the cost of nothing", to adapt
a maybe not fitting saying)

> The memory overhead is negligible. An app that thinks that 16kB/thread is
> too much, should not be using kernel threads in the first place. You could
> argue that it probably shouldn't be using threads at _all_.

I argue that actually sometimes, but usually fail. At least I think
if they really want to use threads it should not hurt the rest of the system.

-Andi
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