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Re: Example uses for read-modify-write operations?

From Philipp Klaus Krause <pkk@spth.de>
Newsgroups comp.lang.c
Subject Re: Example uses for read-modify-write operations?
Date 2019-09-04 14:33 +0200
Organization solani.org
Message-ID <qkoav1$3jf$1@solani.org> (permalink)
References <qknvks$rgm$2@solani.org> <MAMbF.78233$gN2.1096@fx31.iad> <qko70n$r2$2@solani.org> <QTNbF.376844$AR4.14415@fx39.iad>

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Am 04.09.19 um 14:13 schrieb Clifford Heath:
> 
> Perhaps so, but anything that allows you to do a mutex allows you to
> build everything else. Less efficiently, it's true (I used C&S) but still.

Though the mutex you get from fetch-and-add has a limit on the number of
threads waiting on it before it breaks (the maximum value of the
underlying data type), but I don't see that as a big restriction.

On the other hand, with a mutex, the things you build are no longer
wait-free (and Herlihy requires this property).

From the C perspective: You can build a lockless atomic (i.e. one that
can be used safely from signal handlers) easily with CAS, but not with a
mutex (unless there are certain restrictions on signal handlers beyond
what the C standard states).

Philipp

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Thread

Example uses for read-modify-write operations? Philipp Klaus Krause <pkk@spth.de> - 2019-09-04 11:20 +0200
  Re: Example uses for read-modify-write operations? Clifford Heath <no.spam@please.net> - 2019-09-04 20:44 +1000
    Re: Example uses for read-modify-write operations? Philipp Klaus Krause <pkk@spth.de> - 2019-09-04 13:26 +0200
      Re: Example uses for read-modify-write operations? Clifford Heath <no.spam@please.net> - 2019-09-04 22:13 +1000
        Re: Example uses for read-modify-write operations? Philipp Klaus Krause <pkk@spth.de> - 2019-09-04 14:33 +0200
      Re: Example uses for read-modify-write operations? already5chosen@yahoo.com - 2019-09-04 05:14 -0700
        Re: Example uses for read-modify-write operations? Philipp Klaus Krause <pkk@spth.de> - 2019-09-04 14:35 +0200
        Re: Example uses for read-modify-write operations? mark.bluemel@gmail.com - 2019-09-04 08:24 -0700
          Re: Example uses for read-modify-write operations? already5chosen@yahoo.com - 2019-09-04 08:37 -0700
          Re: Example uses for read-modify-write operations? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-09-04 17:10 +0100
  Re: Example uses for read-modify-write operations? Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-04 14:28 +0200

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