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SubjectRe: Good point of Linux over Windows NT
On Mon, 20 Jan 1997, yuri mironoff wrote:

> On Mon, 20 Jan 1997, Alan Cox wrote:
> > > You are not talking to an NT supporter here. Linux SMP is in its
> > > infancy. And NO thats not what async IO means. You have to give credit
> >
> > Linux SMP is quite nicely done for CPU intensive tasks. I/O intensive SMP
> > is poor on the intel port (its quite passable on the sparc) We also have fully
> ^^^^^
> > working async I/O. If you look at clone() and learn to use it right. Note that
> > clone is so fast there isnt an overhead issue.
> >
> > Its not my fault you don't look very hard.
> >
> > Alan
> >
> >
> We are not discussing architectures here but the fact that SMP on Linux
> is in your own words "PASSABLE" - do you actually think that sounds
> anywhere close to "TOP-NOTCH"???
> Y
> P.S. Is spinning in a tight loop in do_select() an example of async IO?

Look at the code. It isn't spinning. It schedules. The CPU time isn't
wasted. Linux is a Unix variant. Unix does Async like this. VAVen do
ASTs (Asynchronous system Trap), NT (borrowed from VAX/VMS) does the
same thing but with another name. Neither is BETTER.

Note that single character Async is BAD everywhere. There is a lot of
overhead for a single byte. That's why old DEC machines had a separate
board with a dedicated CPU to handle Terminal I/O. All editing, control
characters, etc., was done without the main CPU even knowing about it.
That's why strings used descriptors so that when they were finished, they
could be DMAed over the Qbus.

Dick Johnson
Richard B. Johnson
Project Engineer
Analogic Corporation
Voice : (508) 977-3000 ext. 3754
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Penguin : Linux version 2.1.21 on an i586 machine (66.15 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.

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