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Re: string and __thread
On Mon, Mar 31, 2003 at 11:06:28AM -0600, Benjamin Kosnik wrote:
>
> >Does any non-ELF system even have the ability to support this feature?
>
> No.
>
> Furthermore, most of this problem statement/theoretical solution is
> speculation, although well meaning. I'm uneasy about such changes
> without any actual profiling or evidence that there is a problem, and
> that this solves it.
Obviously we want experience, which is why I posted. The problem
is well-known, and has been belabored at length in the literature,
e.g. Herb Sutter's benchmarks. (Let's not nip off discussion of
performance improvements before results are demonstrated; that's
a good way to keep from getting any.)
As it happens, the alternative suggestion I had mentioned doesn't
need special linker/loader support, and already has industrial
demonstration: it's used in the Rogue Wave library. Furthermore,
it can sometimes improve performance even in single-CPU contexts.
Best of all, it's obviously non-disruptive.
That alternative is to test the pointer for equality to the known
empty-string object before doing an increment or decrement-and-test.
I will prepare a patch if Paolo doesn't get to it first.
Nathan Myers
ncm-nospam at cantrip dot org