Re: [patch] SMP alternatives

[Linus Torvalds]

On Wed, 23 Nov 2005, Daniel Jacobowitz wrote:
> 
> I don't think I see the point.  This would let you optimize for the
> "multi-threaded, but hasn't created any threads yet" or even
> "multi-threaded, but not right now" cases.  But those really aren't the
> interesting case to optimize for - that's the equivalent of supporting
> CPU hotplug.

NO.

There is not a _single_ compiler that is multi-threaded, and I'd argue 
that there probably never will be. It's pointless.

There's a _lot_ of really performance-sensitive stuff that will NEVER EVER 
be threaded. You may run a hundred copies of them at the same time, but 
every single copy will be single-threaded.

And this will optimize that case in a BIG way.

This is _not_ about "CPU hotplug". This is _not_ about "threaded apps 
before they are threaded". This is all about the fact that serious 
computation is done single-threaded, and anybody who thinks that 
single-threading is going away is so totally out to lunch that it's not 
even fun.

And yes, Sun will die. Single-thread performance matters a hell of a lot, 
and any company that bets that it doesn't, is a failure.

		Linus
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