Re: [PATCH] Replace completions with semaphores

[Ingo Molnar]

* Matthew Wilcox <matthew@xxxxxx> wrote:

> On Sun, Apr 13, 2008 at 09:05:13AM +0200, Ingo Molnar wrote:
> > there's also another aspect: completions are faster a bit 
> > in theory, because they know that they will schedule most of the time - 
> > while semaphores assume that they will _not_ schedule. (And that's 
> > exactly because the intent of the developer when using a completion is 
> > crystal clear.)
> 
> In practice though, the current implementation is slower. [...]

any URL to benchmarks?

> [...] Of course, that's fixable, and I strongly suspect that the 
> current users of completions simply don't care about speed -- the 
> normal use of completions is in startup and shutdown paths where a 
> millisecond extra isn't going to be noticable.

completions and semaphores act in the sub-microsecond range, not in the 
milliseconds range.

	Ingo
--
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/