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From: Justin Cormack <justin@specialbusservice.com>
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Subject: Re: Transition path for removing lazy init of thread pointer
Date: Mon, 24 Mar 2014 23:44:57 +0000
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On Mon, Mar 24, 2014 at 11:04 PM, Rich Felker <dalias@aerifal.cx> wrote:
>
> At this point we now have two mandatory syscalls at startup on most
> archs (just one where setting the thread pointer is entirely a
> userspace operation). The second syscall is set_tid_address, and it
> seems like it should only be needed it pthread_create is being used
> (to that pthread_join will work), but it serves a second purpose of
> standing in for gettid() too. We could, however, eliminate it in some
> cases:x

Which archs is it userspace only?

Any idea what the performance benefit of the optimisations might be?
Static linked non threaded programs sounds like a good target.

Justin