Date: Wed, 18 Jun 2003 23:38:59 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: threads@freebsd.org Subject: Re: Nvidia, TLS and __thread keyword -- an observation Message-ID: <3EF15A83.D869E0C9@mindspring.com> References: <20030617223910.GB57040@ns1.xcllnt.net> <002101c3352a$e931a7f0$0701a8c0@tiger> <20030618003556.GA2440@dhcp01.pn.xcllnt.net> <3EF02B40.A4BD1EF@mindspring.com> <20030618182638.GA63660@ns1.xcllnt.net>
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Marcel Moolenaar wrote: > 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. If you wanted to save space, you would not be using per thread storage in the first place. 8-). Time is only an issue if you are talking .tdata; the .tbss is all zeroed, so could be allocated as a very large block, with relatively no initialization overhead. > 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... I understand the specification's intent, both the purely technical, and the political. -- Terry
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