Re: [patch] SMP alternatives

From: Daniel Jacobowitz
Date: Wed Nov 23 2005 - 17:20:41 EST

On Wed, Nov 23, 2005 at 02:19:08PM -0800, Linus Torvalds wrote:
> 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.

I get the feeling you didn't read my message at all. Let me try it

Why should we use a silicon based solution for this, when I posit that
there are simpler and equally effective userspace solutions?

Daniel Jacobowitz
CodeSourcery, LLC
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at