Fitting time slices to execution phases

By: Linus Torvalds (torvalds.delete@this.linux-foundation.org), August 21, 2018 4:26 pm
Room: Moderated Discussions
Gabriele Svelto (gabriele.svelto.delete@this.gmail.com) on August 21, 2018 3:54 pm wrote:
>
> One big downside they had was that they could not be executed speculatively

The thing is, properly designed remote atomics for statistics have to be of the type where they are

(a) not ordered wrt other memory accesses (including locking!)

(b) do not return a value to the processor

and then the way you implement them is that they are "scheduled" (to whatever remote atomic engine) when the instruction retires. No serialization by the core what-so-ever, outside of just the queue size for the remote atomics or something.

Then you'd have a "wait for remote atomics queue to flush" instruction for any readers - assuming the reader even cares (which might not be the case). If you really care, you do cross-CPU calls and locking and everybody is forced to do the sync, but for statistics, that kind of caring is so rare that it might not even exist.

Of course, for people who want remote atomics for other things, the rules can be very different. If you want them for refcounting in a GC environment you might have very different synchronization needs indeed.

Linus
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ARM turns to a god and a heroAM2018/08/16 09:32 AM
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    ARM turns to a god and a heroDoug S2018/08/16 11:11 AM
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      It's marketing materialMichael S2018/08/17 03:13 AM
        It's marketing materialdmcq2018/08/17 05:23 AM
          It's marketing materialAndrei Frumusanu2018/08/17 07:25 AM
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          It's marketing materialGroo2018/08/17 01:44 PM
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                Just by way of clarification Wilco2018/08/18 01:26 PM
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                  Just by way of clarification none2018/08/18 10:52 PM
                    Just by way of clarification dmcq2018/08/19 08:32 AM
                      Just by way of clarification none2018/08/19 08:54 AM
                        Just by way of clarification dmcq2018/08/19 11:24 AM
                          Just by way of clarification none2018/08/19 11:52 AM
                  Just by way of clarification Gabriele Svelto2018/08/19 06:41 AM
                    Just by way of clarification Passing Through2018/08/19 09:25 AM
                      Whiteboards at Gatwick airport anyone? Passing Through2018/08/20 04:24 AM
          It's marketing materialMichael S2018/08/18 11:12 AM
          It's marketing materialBrett2018/08/18 05:22 PM
            It's marketing materialBrett2018/08/18 05:33 PM
              It's marketing materialAdrian2018/08/19 01:21 AM
        A76AM2018/08/17 02:45 PM
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            A76AM2018/08/18 12:39 PM
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                      A76Maynard Handley2018/08/18 04:22 PM
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                        A76Maynard Handley2018/08/19 12:22 PM
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                                Fitting time slices to execution phasesPaul A. Clayton2018/08/21 09:09 AM
                                  Fitting time slices to execution phasesLinus Torvalds2018/08/21 02:34 PM
                                    Fitting time slices to execution phasesLinus Torvalds2018/08/21 03:31 PM
                                      Fitting time slices to execution phasesGabriele Svelto2018/08/21 03:54 PM
                                        Fitting time slices to execution phasesLinus Torvalds2018/08/21 04:26 PM
                                      Fitting time slices to execution phasesTravis2018/08/21 04:21 PM
                                        Fitting time slices to execution phasesLinus Torvalds2018/08/21 04:39 PM
                                          Fitting time slices to execution phasesTravis2018/08/21 04:59 PM
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                                      Fitting time slices to execution phasesanon2018/08/21 04:27 PM
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                                        Fitting time slices to execution phasesGabriele Svelto2018/08/22 03:07 PM
                                          Fitting time slices to execution phasesTravis2018/08/22 04:00 PM
                                          Fitting time slices to execution phasesanon2018/08/22 06:52 PM
                                    Fitting time slices to execution phasesTravis2018/08/21 04:37 PM
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                                      Is preventing misuse that complex?Linus Torvalds2018/08/23 12:46 PM
                                        Is preventing misuse that complex?Travis2018/08/23 01:29 PM
                                          Is preventing misuse that complex?Travis2018/08/23 01:33 PM
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                                            Is preventing misuse that complex?Travis2018/08/23 03:11 PM
                                              Is preventing misuse that complex?Linus Torvalds2018/08/24 01:00 PM
                                                Is preventing misuse that complex?Gabriele Svelto2018/08/24 01:25 PM
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  my future stuff will be better than your old stuff, hey I'm a god at last (NT)Eric Bron2018/08/18 03:34 AM
    my future stuff will be better than your old stuff, hey I'm a god at lastnone2018/08/18 08:34 AM
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