Nvidia, TLS and __thread keyword -- an observation

[Marcel Moolenaar]

On Wed, Jun 18, 2003 at 02:05:04AM -0700, Terry Lambert wrote:
> Marcel Moolenaar wrote:
> > On Wed, Jun 18, 2003 at 07:48:09AM +0800, David Xu wrote:
> > > I believe this will add overhead to thread creating and destroying,
> > > How fast an RTLD can be in this case ?
> > 
> > In the dynamic TLS model you would like to delay the creation of
> > the TLS space. Normally __tls_get_addr() gets used for this. In
> > the static TLS model you allocate the TLS when you llocate the
> > thread control structure.
> 
> Lazy binding in this context doesn't make a lot of sense.

It does. In a process with 1000 threads where 1 thread does
a dlopen(), you don't want to create 999 TLS spaces if they're
not going to be used. Besides time, this also is a space
issue.

Note also that I don't advocate what I think we should do, but
what the specification is designed for. People have put some
thought in it...

-- 
 Marcel Moolenaar	  USPA: A-39004		 marcel at xcllnt.net