Subject: Re: Please Revert newlock2
To: None <>
From: Joerg Sonnenberger <>
List: tech-kern
Date: 02/21/2007 13:37:47
On Tue, Feb 20, 2007 at 08:25:33PM -0800, Bucky Katz wrote:
> Joerg Sonnenberger <> writes:
> > As it was said already, the complexity of SA is huge. I think that
> > for most applications the performance gains are much lower than one
> > would expect.
> It depend on the nature of the application. It has been my experience
> that for applications that do significant synchronization the
> performance gains are huge.

That's why I am asking for the type of beast you are dealing with.

> > Large parts of the pthread library can be implemented to avoid the
> > need for context switches with proper atomic instruction support,
> > esp. if UP is all that is needed.
> Yes. That's even more complex than SA...

No, it is not, because you don't have to deal with all problms for it to
work. One of the major differences is that it is that the complexity is
kept outside the kernel, which is a very good thing as it reduces the
impact of any problem a lot.

That said, I'm sorting out the building blocks necessary to do almost
the same as SA without the kernel side complexity. What I have in mind
would help a lot for non-threaded architectures as well, but I need more
time to think about it.