Implementing TLS: step 1
Julian Elischer
julian at elischer.org
Sun Jun 22 23:16:42 PDT 2003
On Sat, 21 Jun 2003, Igor Sysoev wrote:
> On Fri, 20 Jun 2003, Julian Elischer wrote:
>
> > > We can implement such scheme on x86:
> > >
> > > gs -> [ TP ] ---> [ TLS ]
> > > [ struct kse_mailbox ] +-> [ struct kse_thr_mailbox ]
> > > [ .km_curthread ] -+
> > >
> > > When UTS would switch to the next thread it should set thread's TLS:
> > >
> > > kse_mailbox.km_curthread = NULL;
> > > gs:[0] = next_thr_tls;
> > > kse_mailbox.km_curthread = next_kse_thr_mailbox;
> >
> > yes and the last line is atomic.. But remember having a NULL curhtread
> > pointer stops upcalls but it is not the ONLY thing that stops upcalls..
> > A flag TMF_NOUPCALLS (spelling?) in the mailbox will also inhibit any
> > upcalls. 1:1 threads (BOUND) threads, (system scope threads?) set this
> > bit, but they still can have a mailbox for other purposes. (e.g. setting
> > mode flags and stuff).
>
> So NULL curthread is the short term (in UTS only) and atomic method to
> disable upcalls while KMF_NOUPCALL flag is the long term and non-atomic (we
> can not atomically update bit masks in general) method ?
exactly.
>
>
> Igor Sysoev
> http://sysoev.ru/en/
>
>
>
More information about the freebsd-threads
mailing list