Re: clone() <-> getpid() bug in 2.6?

[Linus Torvalds]

On Sat, 5 Jun 2004, Arjan van de Ven wrote:
> 
> ... or glibc internally caches the getpid() result and doesn't notice the
> app calls clone() internally... strace seems to show 1 getpid() call total
> not 2.

Why the hell does glibc do that totally useless optimization?

It's a classic "optimize for benchmarks" thing - evil. I don't see any
real app caring, and clearly apps _do_ fail when you get it wrong, as
shown by Russell.

And it's really easy to get it wrong. You can't just invalidate the cache
when you see a "clone()" - you have to make sure that you never ever cache
it ever after either.

Uli, if Arjan is right, then please fix this. It's a buggy and pointless 
optimization. Anybody who optimizes purely for benchmarks should be 
ashamed of themselves.

		Linus


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/